Know what you mean, about The Knowledge of posts like Alan S, I have come to rely on them as a fund of info, being new to Xantias and having limited experience with motors. I find the history of back posts a gold mine of resources.

On a different note ,For the GTi BX ,we managed to get the tensioner on the alternator belt, to stop rumbling(could not get a replacement) by gently heating it on a hot plate and packing it with teflon grease,this is expensive stuff ($1k for a small tub)but we manged to scrounge some from an engineering firm, thanks Parr and Co.

Teflon grease is a white high pressure ,high viscosity

the bearing is offset from the tensioner bracket and tends to twist when worn,crap design ,but Via la difference,tis French.