Bet if you took it to a repairman who is knowledgeable in featherweights, he could get it all tuned up and you wouldn't have any more trouble.
When we bought mine 10 yrs. ago, it had been restored and fine-tuned. Then the bobbin wasn't quite right so I took it to a repairman who understood these machines very well. When he was done with it, it has run perfectly ever since, and that is 10 yrs. ago.
They just need a few 'final touches.'
Mariah