Yes, I found the same thing with my Class 40, and turning it round cured the problem! Obviously a pick up problem as you suggest.
Incidentally, on first running the loco out of the box, it ran with a slight jerkiness which 'running in' did not cure. Tried the Loksound trick of setting CV54 to 0 then 1, loco ran off quickly for over a metre and, 'hey presto' now 'smooth as a baby's' ! The crazy top speed has been reduced also.