Clutch Type Sure-grip Chatter?

Hi All,

I just had a 741 w/ a clutch type sure-grip rebuilt and now after maybe 200-miles it's making some interesting chattering noises when I turn at low speeds the until it's nice and warm.

Sadly, I forget which type gear oil I put in it after the rebuild. I think it was Royal Purple - which is supposed to have friction additive built into it. Could this be a friction additive issue?

I had it rebuilt by an excellent mechanic so I trust it was done right. Any suggestion on where to start with this, or maybe this chatter is normal?

Thanks.