Damn transtops... I'm actually glad we don't get them on USDM sols. They seem to be more trouble than anything else. But, because US sols don't have them, I don't know a whole lot about them. BUT, I do know that the gears in the transtop motor are extremely weak for the weight load they're expected to bear. The gears strip and/or warp a lot. Might wanna check about that. If it's not the gears or a motor problem, it may well be the computer going. I would just grab the part from the junkyard if it's easily had. Do a search on here for "transtop". There was someone named mariejader who is connected with a shop in the UK that specializes in transtop repair. Hope that helps.
Where are you located, anyways? If you're in Japan I have a favor or two to ask of you.