PWM servo amps, and old servo motors

I am looking for servo amps to replace the 1970's vintage ones on my
tape-O-matic. The X and Y axis have Reliance 457665-MV 3/4 hp motors, type
TR with 6 wires. They are 120V, with a 6.0 amp rating on armature, and a
0.65 amp field rating. I think the Z is the same, but its nameplate is not
visible.

Is a pwm amplifier one that will send high frequencies to the motor that
will harm its insulation, vs other types of amps?
Looking at the Advanced MOtion Controls website, they say of their
amps:
"These amplifiers drive brush-type DC motors or inductive loads at a high
switching frequency and can be configured in various modes and accept an
analog ± 10V command signal." Their literature goes on to say that the pwm
amps have a 22kHz switching frequency.
Just looking to get a bit smarter in picking amps for conversion of the
old tape-O-matic.

Brad


[Non-text portions of this message have been removed]