I've just tried the Clacton to Liverpool Street run, as I wanted a speedier run than with the Parkeston tanks activity. As it turned out, I was going faster in the 66 for most of the way!
Having viewed the front cab fix on the MT forum for the aforementioned activity, I decided to give it a try and followed the instructions to a T. No problems from Clacton to Colchester, but from there after coupling up to the other 321 and changing cabs, I had severe problems with getting the trio moving. I kept losing time due to the 321s not getting above 50mph for most of the way. Going downhill through Brentwood and that general area, I managed to achieve 67.4mph, and yes this was on full power!
Fair enough, there's some meatier gradients on the GEML than I ever thought existed (if anyone ever tells me that's flat, I'll slap them with a smelly fish!

), which will take a bit of oomph to get over. However, surely a trio of 321/3s should be able to overcome these banks without issue.
A gathering of MSTS experienced minds was had during the run, during which we established it's likely that MSTSBin had a hissy fit with the changing to the cab of the front 321/3. This appeared to possibly be the case as the front 321/3 seemed to be making noise but the rear two seemed deadly silent.
Any ideas chaps? I'm not in a rush to try the activity again to be honest, however it seemed appropriate to inquire as to possible causes for this problem.
English Electric loco nutter, you can keep your Sulzers! If it's electric, it had better be an 87!