Alberto, what Ic Racer posted is very good advice.

I would suggest you first check the baseboard first. Usually the base board has been fiddled with when the board is taken off and put back on for moving.

It does take a bit of time to align the baseboard, so take care.

With regard to the negative carrier being out of alignment, sure it can happen, but my experience is that generally these machines are so robust their neg carriers and lens holders hardly ever move.

I would suspect the base board as the main culprit.