Cabriolet top latch motor

[Paul33]

Hi, I have a 997.1 Turbo cabriolet.

I had the brushes wear out in the motor driving the cabriolet roof latch. The motor is not sold separately and a replacement part (ie the whole locking mechanism) is $2,500 in Aus.

It was easy to dimantle the locking mechanism to remove the motor. I found an electric motor specialist to replace the bushes (as I could not remove the wind gear to get to them).

Got it back and the top opens and closes in the right motion and appears to be smooth BUT I am getting a rhythmic noise when the motor runs to extend or raise the hook. The best way to describe the noise is like a small stick snapping and it is every quarter second as the motor operates.

Any thoughts on what it may be?

Thanks
Paul