Suggestion: Visit
http://www.racalinst.com/ate_sys/servo.htm
http://www.si-plan.com/content/products/testmachines/limb.php
http://www.spectralogic.com/support/kbase/index.cfm/fuseaction/DisplayArticle/kbaseID/17/
etc. for more info.

If you need to load test it without a drive, you will have to couple it to another motor and run it as an alternator, with a resistive load.  Without the load, you could at least check the open-circuit voltage, again with it driven as an alternator.

If you really want to keep it simple, try spinning it with a variable speed electric drill (possibly use a bit of sleeving eg heatshrink to couple the drill to the motor), that will give you the open-circuit emf - best viewed on an oscilloscope to check the waveshape and phase relationships of the output phase voltages.  The waveshape could be sinusoidal (a brushless AC motor and more common for a servo application) or more trapezoidal (classic brushless DC motor).  If you vary the speed you can plot voltage against output frequency, to give the o/c voltage-speed characteristic.  Of course, you ideally need to test against a known good motor.

Suggestion: It depends what is needed to be tested. Generally, tests can get very involved.

You can connect another motor or drill to the servo and drive the servo up to 1000 rpm and take voltage readings of the phases. This should give you the KE (Voltage Constant) of the servo. You could then compare it to the specs of the mfg to see if the mags haven't been damaged.

Cameron Anderson
Sales & Applications Engineer
www.aerotech.com
"Dedicated to the Science of Motion"