Hello!
I posted a thread about this awhile back (about how to properly fix them and what to fix them with) and came up with a good solution.
Most trap cases have four strap guides per side. Mine is a little smaller than standard, so it only had two per side, of which 3 had broken off with 1 original remaining. This was actually cheap and easy to fix. Here's how I did it:
1. I drilled out the rivets that had been holding the broken strap guides on. After the drill out, the hole was roughly 1/4", so I re-drilled with a 1/4" bit just to make the hole uniform. I then got two 1/4" hex head screws with one small washer and one large fender washer with locking nut for each screw on the strap guide I needed to replace (in my case 3, so a total of 6 screws/nuts).
2. I found a used leather belt at my local thrift store for $2.99. I measured the hole spacing on the strap guide holes that I drilled out, and they were 2.5" apart. I cut a section of belt that was 3.5". 1" wider than the hole spacing worked perfectly for me. I took an awl and made a starter hole on each side of the belt piece, than used a 1/4" spade bit to drill the hole in the belt to 1/4" on each side.
3. I put the small washer (about the same size as the head of the screw) and the hex head screw through the belt, and then into the trap case from the outside. I secured the screws with nylon insert lock nuts and large fender washers to give them a good "backing plate" so they aren't likely to pull out. I made sure the screws were straight, tightened them down, and presto, new strap guides! By being 1" wider than the hole spacing, it forces the belt to "flex" and give space for the strap to fit through.
This was very easy to do, and I have plenty of belt material left over. I just wanted to share this repair with you all so you can have another resource if you need to do a similar repair down the road. Enjoy!
P.S. The "rogue" screw and washer in the upper right of Pictures 1 & 2 is a hole that I covered to prevent spreading or cracking. I polyurethane all my trap cases, so that's why it looks shiny in the photo. Now all I need to do is load it up with stickers, LOL!