Update: I had a friend come over and help me with the machine, and I think we've fixed it. With a little bending, the brake strap issue is gone, but we found that erase was still not working- the tape was still being pulled away from the erase head into the tape guide during play. As I mentioned earlier, I had screwed down the left/ supply side tension roller as low as it would go, but we decided it needed to be brought down more somehow. While disassembling it to see what we could do, we found that there was a spacer installed underneath the bearing. I don't know if the spacer was reinstalled incorrectly by a previous owner, or if something wore down or got bent (the exploded diagram in the manual doesn't show these washers or spacers it seems), but we decided to try installing the spacer on top of the bearing instead of below, thereby giving us adjustment space to lower the whole tension roller more. Ta-da! Much better alignment, and erase seems to be working properly now.