I need some opinions.

My lathe is 2 years old, been used a lot. It was hard to shift speeds and
the spindle was slipping. I opened up the case and found..a lot of dust.
When I got that out of the way, I found that the moveable side of the sheave
wasn't moving very well. The shaft was clean, so I just sprayed on some dry
lubricant, on both shafts. Immediate improvement.

But... I also noticed that at low speed, spindle sheave fully closed, that
the belt was running about 1/4" to 3/8" below the rim of the sheave. The
belt was tight. On high speed, spindle sheave fully open, the belt was
slipping. And the belt was running about 1/8" proud of the motor sheave.
There were no cracks or breaks in the belt.

I suspect that I may have worn off a bit of width over time, so the belt
seats lower than it used to. Writing this, I realized that I didn't check
that the spindle sheaves were fully closed, or if they were ALMOST closed.

Do I need to replace the belt? If I do, can I safely use a link belt?

Opinions and experience would be welcome.

Walt Cheever