Is the clock ticking when you push the pendulum? If not then it needs professional help. You say the pendulum gets stuck in the middle, does it come to an abrupt stop, if so it needs pro help. I would find out who serviced it and take it back to them. If they are reputable then they will fix the problem. If not you should take it to someone that is.
A clock is a precision instrument and if not repaired properly gears and pinions can shift in moving it and it will not run.
Stevens Clocks, September 2009