this is my commuter bike. last week took the long way home and went up a few hills. after this say 10-12% gradient mashing down on a 40/25 gearing ratio i hit the plateau. where my chain decides to snap back and go into the rear dérailleur. i was going maybe 10mph. the rear wheel is out of true and one of the bearings fell out of the chain. also the chain got twisted. made it home safefly and cleaned the drive train today and saw this:




its an early 80s entry level Japanese steel stamped frame. like i said the rear wheel is out of true and the cassette might be misaligned. about the chain should i replace the missing bearing with a missing link. don't want to buy a new chain, it only has say 1k miles on it.

thanks for advice and help!