Parts are very rough, major bit chatter

[johnl]

I was cutting some Delrin parts on my Millright Carve King today and accidentally ran the bit into an aluminum support.I replaced the bit and then tried run more Delrin parts, but the brand new bit was chattering significantly and the parts look very rough.
I check all the lead screws and none seem to be loose. When a grab the collet of my Spindle and try to move it, it feels like it always has. 
The machine moves in all axes normally.
Might I need to order a new spindle?
Any other thoughts?
Thanks for any advice.

[bLouChip]

I recall chatter in my CK1 sometime ago and after thorough checkout I had some backlash on one of the axes. Backlash under load is hard to detect on those delrin bearing/anti-backlash blocks once they get some wear on them, I recall holding a V-wheel with one hand while trying to manually turn the lead screw coupling with my other hand; this will expose backlash if it's there.  Also, the V-wheel tension should be checked, see the assembly instructions for that, I believe it involves checking for a certain amount of and equal tension of slippage on each wheel; adjust tension with very subtle rotation of eccentric spacers.

[johnl]

Thanks very much @blouchip for your reply. Very helpful.
I'm going to check all V-wheels for appropriate slippage and then I'll check the anti-backlash.

[johnl]

Tightening the V Wheel tension made a big difference. I also tightened the lead screw collars and the motor mounts, which had become a bit loose.
Everything is working very well now.
Thanks again @blouchip