The Erie Mining equipment was purchased several years ago after that operation had shut down (it returned to operation briefly later but has, I think, shut down completely again and for good). The RS-11's, jordan spreader, a crane and maybe something else came to the M&E and have been kept stored in the yard at Lake Junction except when management decides to have something worked on. RS-11 7215 has been restored to service in a unique M&E paint scheme. 7216 has been largely scrapped (see Morristown Diesel Doings thread for some more info). Another 7206? has been on the run-around at Morristown for a few months now - I assume waiting it's turn in the shop after more high-priority projects.
Why did they buy it all - it was there, in varying states of repair (surely some are never intended to run again but to be parts sources for the others) and presumably the price was right. Any answer beyond that would have to come from the M&E and they don't seem inclined to say much.
Ditto the CN Alco (which spent some time on subsidiary Maine Eastern with another of its kind before coming south). It has sat where it is since arrival - it's missing a traction motor - don't know what other mechanical work is required. The other Canadian ALCO is a recent arrival. I'd speculate it's a parts source and then a candidate for razor blades.
Hope that helps a bit.