That is why the maintenance manual requires a hyd power off elevator check flight if the elevator trim tab has been disturbed. I have had one check flight when the setting was not correct and it is a little exciting until you overpower or get the hyd power back on.
The aircraft flys very well in manual reversion, in the 5 different B737-200, 300 and 400 simulators I have used three were very close to the aircraft feel, one was OK and one was so bad the regulator required manual reversion training to be completed in the aircraft or another simulator used.