Anyway to try and fix the tension issues on the other machine ?
Even though it seems it is locking up on the mechanicals the problem can still be in the bobbin area. I am fixing a machine that the bobbin area froze up from old grease and nothing on the machine would move. You would be surprised what can happen with a stray thread.
Try rethreading the machine- a new wound bobbin - new needle and clean the bobbin are