Just got my 4-6-0 back from B'mann - 7 weeks early. They replaced it.
RMorgan

It does seem frustrating. I just sent a 4-6-0 in for repair replacement(wheel fell of pilot truck after 1 hour of running and broke valve gear). Also got a card back saying turnaround would be 8 weeks. I think your right, mine is an obvious replacement, but I don't think they have enough in stock. I sent a 4-6-0 in last August and got the same card in about a week  - the replacement engine showed up the next day- who knows. BTW, I have two 2-8-0's and they are both great engines - only complaint is one of them has a pilot truck that occasionally jumps the same switch - haven't quite figured it out yet. The warranty can't be beat, I guess we'll just have to be patient.

Ain't it great when things go right!

Received a replacement 4-6-0 Friday (Bachmann replaced one that I had damaged - great customer company). Started to check it out and it derailed at first left-hand turnout. Lead truck was tracking left when turnout was set straight and jumping the  Other turnouts shaky but no derail. Checked track and turnouts - all OK. Checked here and other forums (fori?) for advice. Got several good tips. Tried easy ones first. Adjusted screw on lead truck ( It appeared loose, so I tightened it slightly.) Still derailed on retest. Moved on to other screw adjustments - suggestion was that rear of engine sat too low and raised front end. There are three screws on the under-carriage. I tightened the rear one ( to raise the rear end) and loosened the center and front ones slightly ( to lower the front). Tightened the leading truck screw again slightly to dampen the wandering. Retest totally successful!! Running for one hour now without a derailment!! There were several other suggestions for curing these derailments, that hope I won't need.

Thanks to everyone who had contributed to previous posts on this subject - you saved my weekend.