Hey Sed6
Thanks man! Boy did they need cleaning! I've only had time to clean 10 pieces of straight track for now, but it seems to be working.
Both locomotives starts and drives fine - even at low settings on the control. The 4563 locomotive has always had a bit of a mind of its own, even with clean tracks. Hence, it drove satisfyingly for a while on the clean tracks, then suddenly stopped and wouldn't go. I fiddled with the controls for a bit, trying to adjust the connectors and such. And ZOOOM! it went of - highest speed. Heh, it's working fine now. I'll keep cleaning and testing and return if I continue to have problems.
All the best