swampwalker... I do know that the local respected techs have a 2-4 month backlog.Yes, I think that is quite common. I have a piece in now with an expected 12-week turnaround. But that's for a reel-to-reel tape deck.
On a warranty repair, I would certainly expect to have some reliable information about the problem within four weeks. For a manufacturer to state it is "not sure yet why the problem is happening" after a month is not acceptable, imo, which is why I suggested getting the dealer involved.