Z-Axis Knee Woes

Hi folks. I'm retrofitting a G3102 Grizzly Knee Mill, a smaller type
mill somewhere bigger than a drill mill, but smaller than a full
bridgeport.

I just finished my Z-axis, after success with X and Y. I decided to
motorize the knee for various reasons. I'm using Camtronics 600-in-oz
motors and a 2:1 ratio on the pulleys.

The knee is driven by a shaft that is at 90-degrees to a jackscrew.
The shaft is connected to the jackscrew via a set of helical spur gears.

Here are my problems:

(1) the motors aren't powerful enough, apparently, to raise the knee.
They stall and eventually cause my geckos to fault. I'm pretty sure
I have the "limit" set to Max on the geckos.

(2) when lowering the knee, the motor turns and every now again
there's a 'thump' from the mill, as if the knee is not lowering
smoothly, but in little increments.


I guess I have two options:

(a) go to a higher ratio, but 2:1 was the most practical. 3:1 is
possible but expensive, and anything more is really not possible due
to pulley size constraints.

(b) counterweight the knee. I think this is complicated and probably
not a good idea.

In either case I'm not sure it would solve problem #2. I'm currently
at a loss on how to proceed. Any suggestions are greatly apprecaited.

Thanks,
Jake