Drivers electric seat adjustment issue

Evening All,

I've got another issue I'd like some help with.
I've just noticed that my drivers seat doesn't function so well.
It adjusts electrically in all directions perfectly except when lowering or raising the seat. The sound produced is similar to that of a failed window regulator (gears bouncing). Any ideas on what I need to replace?

Thanks in advance

Can only be the rise and fall motor or the operating rod. You will have to look.