That "shutter's completely seized up" line hits close to home for me. I had a similar thing happen with a Yashica from the early 70s I picked up at a flea market a couple years back. The whole mechanism was frozen solid, took me nearly a month of careful cleaning with lighter fluid and a lot of patience to get it moving again. It's frustrating when you find something that looks so good on the outside but the insides are all gummed up from decades of sitting around. Hope you can get that Polaroid working again, those old cameras are worth saving if you have the time and steady hands for it.