I recently received a TS-711a that won't power on. The previous owner hadn't used it for 6 or 7 years. He said that it worked fine when he put it away. He plugged it in and it stayed on for a few minutes and then just quit--no smoke, no pops, no smell. If I can figure out what is wrong, I'd like to try to fix it myself. That being said, I have no illusions regarding my lack of talent where electrical repair is concerned. Where and what would you suggest I start? Thank you.