Sebo X1.1: Height Adjustment Motor and Main PCB Board Failed?

[macman]

• Tweet

I have a X1.1 in with apparent ride height servo motor failure. The height adjust wheel won't lower, so it makes an awful grinding/vibrating noise on carpets as the brushroll digs in. I have an X4, so I swapped in the known good servo motor, but it still won't adjust down.
I know the servo motor has failed because I then tried it in the X4, and it doesn't work, so I need to order one of those. But do I also need to order a replacement PCB main board as well? It's the later type, NPPSTXSNM-3. Is it possible that both have failed simultaneously: could the servo motor have blown and taken out the main board PCB with it?
The little magnet is in place, so that is not the issue. Are they any other components that can affect the height control: such as the power board PCB? What else can I test?
I would rather have a diagnosis at the start than start swapping components in until it works. Thanks.

[macman]

PS: having read several posts relating to this, the issue is not the brushroll being worn or gone 'soft': it was replaced less than a year ago.
The belt sensor also seems OK, with both magnets in place, and it turns freely.

[MVacs]

But do I also need to order a replacement PCB main board as well? It's the later type, NPPSTXSNM-3. Is it possible that both have failed simultaneously: could the servo motor have blown and taken out the main board PCB with it?

Highly unlikely.

[macman]

It turned out that the servo motor had failed some time ago, but the customer had continued using it on carpets for several weeks, even though it was making a hideous noise. What seems to have happened is that the brushroll was digging in on carpets (due to the higher resistance) and stalling. But the motor kept turning, and this made the front drive belt strip most of it's teeth.
Not quite sure why the brushroll stall device was not kicking in and shutting the motor down, but once I replaced the servo motor and the small front belt it was OK again.