Sliding Shower Door Bottom Guide, 1/2 in. Channel, Plastic Construction, Gray, 2-Fastener Installation 2-pack)

Removing the glued on guide with a putty knife would probably be best choice, if you want to go the long route you could remove the upper track but you would need help keeping the doors upright, then install the new wheel kit(s) hopefully without needing to adjust their height, reinstall the track and doors. 

Thank you for your inquiry regarding this item from Prime-Line Products. the guide needs to be removed so the door panels can be angled away from track to lift it clear of the opening. You can then reinstall the doors and remount the guide.

The holes are fairly well precisely one and three-eighths(i.e.: 1&3/8)inches apart. With that measurement taken from: center-to-center(i.e.: from the center of one hole to the center of the next hole)if that helps. However, as I've advised previously, I affixed my shower-door guide using exterior-grade double-sided foam tape--without use of any screws or other hardware. If doing so one wants to take great care to thoroughly clean the bottom metal rail(probably made from aluminum and with allowance for complete drying afterward)before ever applying the double-sided tape. I used, if memory serves me correctly, 3M brand of exterior grade double sided tape. The main reason for that being that such a grade of adhesive will, supposedly, hold under temperature and moisture extremes. It's been close onto 2 years since I used such a mounting method and it still seems to be holding strong. Am also reasonably sure that use of something like "Gorilla" brand glue would do as well--not-to-mention the sort of adhesive used to apply ceramic tiling. And one other caveat: If using an adhesive to apply this door guide try to allow at least 24 hours for same adhesive to "set" and "cure" before using that shower.

I bought it a couple of years ago and it has worked well. As long as you can line up one screw hole with the existing, and screw it in tight, that may very well do it.

The holes are 1.5” from center to center of holes.

Thank you for your inquiry regarding this item from Prime-Line Products. The hole centers are 1 1/2" apart. You can contact the manufacturer directly with your questions regarding this item, or any other product manufactured by Prime-Line Products by calling their toll free number at (877) 649-9740, or by contacting them by email at info@primeline.net.

That kind of depends on what sort of material the bottom rail(onto which this guide will typically be fastened)of your shower stall is composed of. Same rail in my stall is of aluminum, which I would guess is similar for about 90%+ of shower stalls made in this country, and those two holes you may be able to visualize(along the bottom side of the guide)are where one would normally use as a sort of template to drill guide holes in that bottom aluminum rail. Seem to recall that this kit came with at least 2, pan-head machine type screws, with which to attach the guide to the bottom aluminum rail. Whether or not the instructions indicated so: when drilling holes for these types of screws it's always best to start with a hole of 1/3 to no more than 1/2 the diameter of said screw. Otherwise, if drilling a pilot hole for such a screw anywhere close to the diameter of the screw, one tends to find that the screw will never fasten snugly/tightly. But there is yet another way involving adhesives. I decided to go with double-sided foam tape(rated as exterior grade and supposedly maintaining its adhesion through the proverbial boiling summer sun, rain, sleet, snow, and ice). Actually never have attempted to stick something up on the outside of our home with the stuff but thus far that foam, double-sided, tape has held that shower door guide in place for nearly 1&1/2 years(and literally hundreds of showers). But be advised that I took very careful preparation of the surface(of the bottom aluminum rail)onto which I stuck that tape. Starting with scrubbing vigorously at the rail with steel wool and/or a "Brillo" pad, so as to remove all crud/oxidation from the surface, then flushing the surface with rubbing alcohol(it dries much quicker than water), allowing the surface to completely dry, and only then applying the double-sided tape finishing with the guide on top of that. AND finally allowing the adhesive tape 24 hours to dry/"cure" before running any water in the shower stall. Have also heard that some handyman types have found "Gorilla" brand glue to work well for such a purpose--with the proviso that the same sort of surface preparation be followed carefully(especially allowing the glue to dry for a full 24 hours before getting any water on it).

Thank you for your inquiry regarding this item from Prime-Line Products. This item comes with four sheet metal screws #8x1/2" PHIL PAN ZINC. You can contact the manufacturer directly with your questions regarding this item, or any other product manufactured by Prime-Line Products by calling their toll free number at (877) 649-9740, or by contacting them by email at info@primeline.net.

I just used the old screws from the broken piece that I had.

Thank you for your inquiry regarding this item from Prime-Line Products. The height of this guide measures 1-inch, when measured from the underside of the base plate, to the top of the tallest part of this guide. For faster service, be sure to take advantage of the CHAT option located in the lower right-hand corner of your screen, where you can quickly be connected to a representative for assistance. Otherwise, you can contact the manufacturer directly with your questions regarding this item, or any other product manufactured by Prime-Line Products by calling their toll free number at (877) 649-9740, or by contacting them by email at prodtech@primeline.net

The height is 7.438 inches.

1.1/4” H 2.5” W

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Truthfully don't know. Sounds like a procedural problem that Customer Service might have fix for.