(ET) Belt slippage

[Bill <wilbett earthlink net>]

I used my E-12 for the first time this year and thought I had lost
power. It was slow going in D2. I had given the batteries a prior charge
and they checked out OK with the hydrometer. So I looked at the drive
belt. It is pretty tight but was slipping. The belt is old and the sides
are shiny, but it has no tears. I'll tighten it up, or maybe get a new
belt, but I'm worried about the motor bearing with so much side force
from a very tight belt.
    Any recommendations? Has anyone rigged up an idler pulley to get
more wrap on the motor pulley? I know the present design works, but the
belt size seems wimpy to handle all that power,

Bill/NE Kansas