240 alternator belt keeps slipping

My son took his '92 240 to a local shop to have a bolt replaced holding the
alternator on. A week later the belt still slips and now the shop says the
alternator bushings need to be replaced and there is no way it can be tightened.
I have to admit that 25 years of driving 240,740,940s I've never replaced
alternator bushings (that I know of. I can see how the belt might be out of
alignment from the bushings but I would think it could still be tightened...
I'm not sure I believe the shop. I get the feeling their mechanic did a poor job
and now they're jerking my kid around. I haven't weighed in yet. I want to get a
little more perspective before I do.

 

These bushings are usually shot by around 100K miles/10 years or so. I
replace all of them as a matter of course when I go through a RWD Volvo,
they're not expensive or difficult to replace. When they wear out, you
get exactly the symptom you describe.

 

Interesting, my 360 alternator bearings were a bit rough after 200K
miles (brushes or regulator failed so got it overhauled), but it didn't
cause squealing. However my 95 940 squeals on full lock, do you think
new bushes will help (presumably PS bushes)?

 

REPLACE THE BUSHES IF THEY APPEAR OUT OF ALIGNMENT Look along the belt is it
straight or twisted ever so slightly are the pulley if so as said replace
the bushes

 

A worn or poor quality belt is more likely to squeal, but bushings that
are worn to the point that alignment is off will greatly accelerate wear
of the belt. The bushings are only $1.75 each from FCP Groton, not sure
why anyone wouldn't just replace them all at once.