indesit is70c loose drum?

Hi,
Replaced the bearing and rear fan impeler of my indsit is70c condenser tumble dryer yesterday. All went fine until ,as i replaced the top cover, the drum is not sitting over the front mount (or front bearing i suppose) and on turning the dryer on, the drum is not moving at the same speed as previously.
If i grab the rear of the drum i can locate it, but once released it just slips backwards.
It is almost as if the front of the dryer is on an angle?
Any ideas