Splendide washer dryer combo knob

We just bought a used rv and the right knob is off on the washer /dryer. We  can't just put it back on because the inside is off center so the knob won't go on all the way and just falls off. We've googled it but no suggestions work. Has anyone had this problem and how did you fix it? We certainly don't want to replace it -I'm not even sure how we'd get it out! And if we could just get the knob on I'm  sure it would work. Thank you