Hi (and welcome!)
BTW, it's Sectric, not Sentric.
It's almost certainly due to what John says - stopping and starting, as synchronous clocks only either run correctly or stop!
For a start, no oil or grease in the movement at all; it's really better to completely dismantle the movement, wash everything apart from the motor and oil with the correct lubricant, washing it assembled is a bit like having a bath with your clothes on
As I guess you're not completely
au fait with clock repair then try just oiling pivots with car engine oil, removing the rotor and oiling the pivot with 3-in-1 or sewing machine oil.
Worth a check to see what fuse is in the plug - should be 3 amp.