Electric window problem on Xantia HDI

[HDI]

The drivers side front window won't fully raise and even if assisted manually to the fully closed postion it still drops within a short time. It's only by 6mm or so but it still causes alot of wind noise.
Is there a typical problem that causes this fault or do I need to change the whole window mech?

[white exec]

Anti-pinch (current-limiting auto-stop, if fitted) may be operating if the felted window channels have become tight. Lubricate side and top channel with dose of WD40, and see if it helps. Other than that, it's a strip-out job.

[Hell Razor5543]

Silicone lubricant is better, as it is also waterproof, so should remain even after a few downpours. You would need to re-apply it every year or so (as it gets worn away).

[HDI]

OK, the window has obliged me by failing completely now so, can anyone confirm whether or not the window mech from an X1 TD will fit an HDI? Asking because I have a parts donor X1 at my disposal.