RIP MP15-DC?

So I ordered a new motor for my MP-15 DC switcher loco on Monday from Atlas. It got here today (Wednesday). The one of the leads had broken off the old one and I didn't have the soldering skills to reattach it. I was excited and put in the new motor only to find it didn't work.

After an hour or so of playing around with it I determined that my decoder is probably the issue. I recall some shorting last time when I was last trying to get it to work with my poorly connected motor lead. At first the decoder was very flakey, I couldn't even read back the address, the motor would run at full speed even when the throttle was off. I ended up resetting the decoder to the manufacturer's defaults on the programming track and it behaved a little better. I was able to read the default address back and got a value on a CV read once out of maybe every 10 tries. After putting it on the track, turning up the throttle, nothing happening and putting it back on the programming track, a few times I finally got it to go forward; however it doesn't work in reverse. I replaced the decoder with the DC circuit board and everything works fine.

Now I am trying to decide if I want to try and buy a new decoder, or a whole new loco, or if I want to put another few hours into playing with it and hope that reverse starts working as magically as forward did.