I have a Bendix two speed that I rebuilt and have rebuilt them for others. I had to buy two junkers on eBay for missing parts. They didn’t make it very long because they came out with the kickback, which worked much better than their manual 2 speed. It’s valuable, especially with the cable, clamps and shifter. The brake is weak, the brake has a long back push before it engages, the brake has horrible modulation, it’s hard to adjust it to shift, blows up if it’s run on trails and overall doesn’t work very well. If you rebuild it, you will probably think you screwed up because they are so hard to adjust. You will wonder if it’s right. What I do after I rebuild one is to not attach the cable. I hand pedal it in a stand and move the tiny shifting rod in and out by hand. If it shifts, which it always has for me like that, then I know that I just need to fiddle with the adjustment. It takes micro turns of the adjuster to get it right and can easily go out of adjustment from cable stretch, or clamp movement. Their pretty easy to rebuild. Be careful with the tiny shifting rod with the micro fine threads. It’s easy to strip the threads reassembling and adjusting. One of my buddies started to rebuild his, stripped the shifting rod, found a NOS one on eBay and started to rebuild it again. When he rode my bicycle and another one I rebuild he lost enthusiasm and didn’t finish. He said he was excited to get it working but when he rode the bikes and saw how bad they were he gave up. They work but to me their just a novelty that a lot of people who don’t have one think is cool. I suppose they are cool, vintage fine American machining.