Triumph Sprint ST 1999- alternator problem

It seems that one in xx of these develop a problem with the
alternator, or alternator drive. If I'm right, alternator drive has
been altered for the 120HP catalysed version, as an "improvement". My
bike has covered some 32000K and the alternator is now very noisy, to
the point I dare not ride anymore. When the bike was new, it sounded
like a simple engine vibration which I thought to be characteristic of
the triple's "character". It grew progressively worse and one trained
Triumph mechanic told me it's the bloody squirrel running in the
energy-producing barrel that gnaws its teeth. No way to find any
technical literature about Triumph: it seems Triumph do not encourage
any mechanical initiative and technical info is kept under the lid.
Even taking off the pump assebly under the fuel tank seems to request
a strict procedure. Can anyone help or suggest something?