OK, by popular demand, I have copied and pasted some of my earlier comments and posts regarding problems with the Robart 615 retracts, and solutions I have found to improve them:

"I have uncovered another cause of unwanted rotations: the molded 'trunion' becoming worn and the screws which hold it into the housing becoming loose. This in turn allows the trunion to wobble in the housing, the the gear to have excessive slop and play, and will allow it to slip a tooth. As the trunion becomes worn, the screws become more sloppy and become loose easier, and can never really be tightened. The old solution was to replace the trunion, but even new ones do not allow you to tighten the screws too much or they will strip out.
SOLUTION: I drilled out tapped the screw holes in the trunions to 5/16" x 18, and installed Keen-Sets( 5/16 x 18 ~ 10 x 32), which are simlar to Heli-Coils ( which could also be used instead ). Now, I have a much larger metal surface against the plastic housing, and the mounting screws can be tightened VERY tight without fear of stripping out."

"In an earlier post to this thread, I stated that I had found a solution to one of the problems with the 615s: that by installing 'KeenSerts' into the trunnions (plastic strut housings) I had eliminated some of the slop, and gear slippage. Having flown with this mod for several weeks now, I can state that this is a worthwhile mod, and that it has greatly reduced downtime due to damaged landing gear.
The problem with the unmodified trunnions is that the mounting screws work loose, allowing more gear play and slop. Eventually, the plastic trunnion wears and the screws cannot be tightened. Using the KeenSerts virtually eliminates those problems.
I few days ago, a reader of this post sent a PM to me asking for a picture of what I did, to clarify it to him, so here it is. The picture is of a modified trunnion (KeenSerts installed on both sides), with arrow pointing to where the KeenSert was installed on one side, and as well as a KeenSert which has not been installed (with thread dimensions).
I get these Keenserts from my place of employment, and cannot provide anyone with info on where to get them. Possibly, a place like Micro Fasteners has them, or some other hardware/ fastener supply place."

"Anyway, the Keenserts do not solve ALL the problems with the Robarts, but sure are an improvement. I think part of the problem with the bending links is that the trunnion twists (due to slop as mentioned above), thereby exerting more pressure on oneside and consequently, one link. As this link is now absorbing more stress, it buckles, which then induces more stress on the remaining one and it buckles also. I have had occasions where only one buckled, so while I don't think this mod will solve all problems, it certainly is helping me out. BTW, my Corsair weighs 8 lbs, 10 oz, and as long as my landings are not too abusive, the retracts are holding. I have even been making some carrier style landings lately, where I have full flaps, fair amount of throttle, hanging on the prop slow, and let is slowly drop to the 'deck', where it promptly does a little bounce, and has a relatively short roll-out. This style of landing used to take out a set of links, but no more.
And, Luke is right, a google search will turn up lots of sites, some even with instructions on how to install them.."