Strange vibration when going uphill

[sv1cec]

Hey guys, long time away, but I am back with a question. First, the facts:

BMW X5 E53 2005 3.0l diesel.

A few years ago, I got the trifecta symptom, three lights on the dashboard. Taking advice from this board, I removed the actuator motor from the transfer case and turned the plastic gear 180 degrees. Problem solved.

Now, recently, I have observed, that when going uphill, I am getting a strange vibration in the car. As if a pulsating effect is taking place. Is this a preliminary symptom of the actuator gear failing again? Shall I order a new, metallic gear and replace the plastic one, once and for all? The truck was diagnosed a few days ago, and there are no faults stored.

Ideas will be greatly appreciated.

Rgds