I have a Olympus OM40-Program 35 mm camera and the film advance lever is stuck on it -- it won't budge for me to reload film and/or advance. Does anybody know why this is or how to fix it? If so would it be an expensive fix? And would it be a simple DIY fix if I opened the camera up or should it be best left to the repair-technician? Any knowledge or advice on the subject is much appreciated. Thank you!