Z-axis motor torque

[beacon14]

Hi folks,

We occasionally have a problem where the Z-axis will stall out when raising up above the area where we do most of our moving. I suspect it's due to the corners of the unistrut not being as worn in that last few inches of travel as they are in the lower few inches. A little lubrication usually solves the problem.
My question is this: How much torque is that z-motor supposed to have? While investigating the problem today, I grabbed the screw (it's a ball/screw drive on a PR48/96, about 3+ years old) and I was able to make the motor miss steps just by holding the screw while the motor was trying to turn it. I didn't think I was grabbing the screw all that hard (I found this out while holding a rag and cleaner to the screw in an attempt to clean it while it was turning). It seems rather weak. Is there a way to measure the torque to see if there is a problem?
Thanks,
David B.

[tlempicke]

Internal to that little motor is a permanent magnet. If it gets weak the motor gets weak.
On many of the Oriental Motors is a label saying that you should not ever dismantle the motor. This is because the motor is magnetized AFTER it is assembled and if you take it apart much of the magnetism goes away.
I know you did not take your motor apart, my point is that it probably has lost some of its magnetism either through age or being stalled or just because it felt like it. Fortunately it is the smallest and therefore least expensive motor on the tool.