I also had E172 yesterday sounding quite poorly, not too sure what's going on with those Es because all the WVLs at RR seem to be fine.
The Es are looking very run down! most days you see the back engine compartment hanging up and oil stains. The contrast when you see a classic E400 on the 241 is amazing!
In fact there is contrast in terms of exterior paintwork and mechanical wise between the 147 E's and the 150 branded T's of which both buses were refurbished back in 2016 by the same people at HD trim and the 150 buses are currently in so much better condition than the 147 buses.