Wiper trouble

I have some issues with the wipers on my 1996 300 tdi Defender.

I have isolated the problem to be with the motor, since wipers move easy. With a little help (a knock from at screwdriver or little hammer) it starts and runs normally. Without help it will not start unless I turn to max speed.

Is there quickfix for this problem, or do i have to change the motor.

There is two screws to keep the motor cover in place. Can the slution be to remove the motorcover, clean up and lube the engine?

Might need a lube job, or maybe the motor brush holder/s is sticky, hence the knock frees it up?