There is likely a fault with the power supply circuitry - unfortunately the parts and labour to fix this cost more than the price of a new one, so for that reason repairs are not normally carried out.
The most likely components to fail in the power supply circuitry are the electrolytic capacitors - a local electronics expert can remove test, and replace these for you. They can also test the rest of the circuitry for any other defects.
Hi Dan, just checking in on your question. How did things turn out for you?