super charger losing power

what started with an occasional whine from the belts, has now progressed.
The tensioner pulley is looking loose, the belts are whining, (obviously need to replace the tensioner) but now the boost on the super charger seems to be dieing as-well.
I owned and worked on a Pontiac Grand Prix GTP, but wrecked it last yr. Recently bought this one but don't know how often anything was serviced, and if and when the oil in the supercharger was last changed. I'm missing the boost of power when I put my foot down :(
My question is, what do i look for in regards to power loss in the super charger ?

I would suspect a Supercharger clutch, belt, or pulley.
You might do a smoke test for any Intake leaks.
How long was it setting around?

i would def change the belt...it may be loose. If you dont here any rattling, the SC coupler should be good