[OT] ABA acc. belt adjustment - how?

[mk1mark at gmail.com (Mark F.)]

The accessory belt on my (98) ABA swapped 86 slips & squeals when it
gets wet.  Anyone know how to add some tension to the spring
mechanism?  The spring tensioner doesn't look to be adjustable at
first glance, but I would expect it to be - right?

Anyone have a PDF Bentley scan of this procedure?   (or the whole
thing!)  I should probably buy a Bentley for it, but I don't
anticipate holding onto this car for too much longer...

Thanks,

Mark.
75
82
86 - 98 Jetta w/ a Scirocco body...