DIY circuit board replacement

I guess that depends on how handy you are.  Obviously, with the right skills, it can be done.

If you are sure the charging circuit is bad, you will have to have a MTH service station repair it. The circuit is built into the main PS-2 board, and MTH only sells the boards to service centers.

So much for do it yourself. I can still operate the engine, but the battery doesn't charge. I've been using another PS2 engine to charge the battery when the one in the Hudson wears down.

Have you considered a BCR

Mort

Been there, done that. It doesn't work in the engine. If I charge the BCR in another engine and put it in the Hudson, it works fine, until I stop it! It doesn't hold the charge. I contacted Wayne Renga at J&W Electronics about it, and he informed me that the recharging circuit board needed to be replaced.

As John says, it's a question of how handy you are.  Do you want to poke around with a meter and possibly a scope (if you have one)?  If these are 3V PS2 boards where the boards come apart, it's likely what failed is only on the smaller power board.  One idea is to swap the power board from the known good PS2 boards to confirm this. Then (and here comes that handy part again) you can troubleshoot the area around the battery connector (comparing to the known good board) and possibly find a DIY replaceable part.

Hoo boy! I'm handy with old school postwar - MPC Lionel, and even Williams to a degree. But this looks a lot more complicated than that. I've never had to replace a circuit board. Perhaps I should leave it to the professional rather than fumble around and make things worse.

You are being smart. I have seen some guys, with all good intentions of checking a board out with a meter, not really knowing what they were looking for and shorted out the lighting circuit, so also having to replace the board now he had to replace every bulb in the loco!