You have a cracked or worn capstan gear. These pieces are made of plastic and break or wear easily if the deck is mishandled (either by physical abuse or tape misloads). I had this happen about 8 months ago....got it repaired by SONY Service Station here in Tokyo for 188,000yen (about US$165), my LCD was all fucked up too (from the deck being taken to Fuji Rock for three days in the rain)...they replaced that and the button controller board for 100,000yen in the same repair($85), they also did some other things like replaced all the inputs and output jacks, cleaned and aligned the transport and head, and gave me all my used parts back, the damn thing had a 22 point checklist and a technician hand stamped document. Prodigital does it but I think the repair is on the order of $200 (which includes cleaning and alignment). So, you got two options.....
Prodigital in PA:http://www.prodigitalinc.com/Sony Service Station (Sony's service department) does it in Akihabara (Tokyo), I do not know how to deal with them if you are overseas):
http://www.sony.jp/support/p-audio/contents/info/index.htmlI could do it for you, but shipping will be at least $15-20 each way, including insurance.