Help with older MTH loco

That certainly is a bummer!  Did MTH normally use wire nuts on PS engines, or is that someone's repair/modification/removal project?

As indicated by the board in the picture, the box flap, and the "-0" at the end of the item number, this engine is only equipped with an electronic whistle, not Proto-Sound. 

MTH typically used wire nuts on the ground and center rail connections inside of their engines from that era.

How big a deal is upgrading to ps 2 or 3?  Is it something I might could handle?  The biggest thing right now is to make it go.  I am planning on removing the chassis to check the wires in the loco itself, but what else could it be?

As it turns out, I upgraded that exact locomotive to PS/2 a couple years back.  It's possible, but there will be some mechanical surgery, it's not a drop-in like many are.

You'll have to hog out the connector recess in the locomotive and also relocate the two diodes on the tether PCB.  There isn't enough room for them, even after the alterations.  I moved the diodes, then cut down the connector PCB to fit.  Next, you'll have to "roll your own" tach sensor mount as the stock one won't clear the shell.  I located mine on the lower side about 7-8 o'clock looking from the back.  I just made a mount from small pieces of fiberglass and used CA adhesive to glue them to the motor directly.

Once you have it running, it's a nice running unit, and it does have great smoke.

P.S.  The other posts are correct, you do not have ProtoSound, just a basic whistle/bell board and the DCRU reverse unit.

DC?

Taking the seller at his word, if pushing on a circuit board made it move it could be an intermittent contact.  Since it sounds like you're going to inspect the wiring/connectors, take a look at the circuit boards for a cold solder joint or where it looks like the components leg has come loose from the solder blob.

I'd also think you could buy a used DCRU board set for a fraction of the PS2 upgrade kit - hmm, I wonder what GRJ did with the one he upgraded .

It looks like a 4 pin tether between the engine and tender. Does the tender have a roller pick up? With the engine alone on the track there should be track voltage on 2 of the pins, (inside and outside rail) The 2 inside ones or the 2 outside ones, I can't remember for sure which. Anyway the other 2 pins will have the DC current going to the motor . maybe you can check the pins for voltage but not so easy if the tender doesn't have a center rail pick up. Wiggle the tether.

The two outside pins are for the motor, the two inside pins are the rails.  If you're looking at the tender connector facing you with the tapered corners up, the second from the left is the center rail, the next one is the outside rails.  The two outside go to the motor.

FWIW, the pins on the engine tether connector often crack their solder and aren't connected.  If you inspect the tether connector and perhaps touch up each of the pins with solder, you may fix it.  You can find out if this is the issue by just plugging in the tether and wiggling it a bit as you try to run.  If the locomotive starts moving as you wiggle, you have probably found the issue.  The tender tether connector wires occasionally break, but more often it's just the solder on the locomotive side.

I probably can come up with a replacement tether if you need one.

Well, as it turns out the no protosound thing is a deal breaker.  I asked my son if he'd be ok with an engine that just had a whistle and no other sounds.  He said, no, he wanted one with all the sounds.  Hey, at least he was honest.

the good news is that even though the no sound thing was my fault the seller is more than willing to take it back!  That is a first class seller!  By chance he has a 2-6-0 in perfect working order with proto 2 right now.  We will try to get it instead.

thanks so much for all the suggestions, you guys are awesome!

That's great that you can return it for a better choice.