I bought a Technics SA-AX6 in 1999. It worked flawlessly until six months ago when it suddenly began overloading at medium to loud levels. It now simply overloads under any condition. the wires are not crossed etc. For example, the unit will overload within 2 minutes even if it is completely in the open, on a table by itself and only has two speakers connected. It works great at any volume for 2 minutes then boom it's done. What is wrong with this unit and what should I do?? Any suggustions would be greately appriciated. Thank you very much.