How can I get replacement parts for the interior slide mechanisms?

I have 2 units, a 3650, and a 5000. The 3650 runs and ejects continuously without stopping to scan, and the 5000 jammed due to a broken tab on a plastic stop/catch which I am including a photo of in this message. After opening both cases, I realized they are mechanically identical, and so I borrowed the non-broken catch from the 3650, and replaced the one on the 5000. It now works perfectly again, but it would be great to get a replacement part, and possibly either a new motherboard for the 3650, or a suitable replacement. The problem is, I can’t find ANYWHERE to buy any of these items. Can you help?