Bob, I didn't vote but I will offer a bit of advice. The light seals in my C330's back died over 10 years ago. There's nothing left of them. But it does not leak light--even with MACO infrared film. I think you should shoot some film to be sure about yours, but mine is light tight without any seals in place.
As for the shutters, you need to give them some exercise. Cock and fire them at each shutter speed numerous times continuously to loosen them up. I once didn't use my C330 for 4-5 years and the shutters were very sluggish. A bit of exercise had them working again in short order.
Give all this a try before you sell it cheap or spend money to repair something that may not need repair.