I know the MTBF on the Type 8s has gone down, so that is why there are more single car or 7 & 7 trains out and about.
What the Type 8s need is a warm sunny climate or to be tucked under a warm blanket at night. In past years they have packed the tunnels with train sets to keep them out of the cold. Now it seems the only place has been the Brattle Loop and I think five two-car sets, of any combination. North Station yard is also a storage yard but with the portal there I would guess it is not the warmest place.
JoeD