That is the nature of hacking.
You don't even think of walking away from one of these before it cools off.
If you do then thats on you.
AND
since I did succesfully raise the temperature without melting plastic structures
I concluded it would be feasible if the nylon plastic gears were replaced with metal gears.
I ruined ONE nylon gear running heaters at 390 degrees.
I would not have let the heater go above 350 if it had not been for the question of
COULD we use the 370 degree BROTHER toner ...not just 340 degree HP toner.
And as far as speed control goes.......
I didn't sprinkle any spice on a 555 to make PWM.
I just told the MOC3020/BTA24 triac circuit hanging off a PIC16F628 pin to stop...wait a few seconds...then
go. I figured I already had triac heater control so it was simple enough to control the motor.
All parts ...soup to nuts cost about $12 for heater and motor control by one PIC16F628 with an LCD
to keep track of settings.
http://www.learnmorsecode.com/laminator/pic/index.html
Noting the pictures show the hot press and not the laminator in use.
The only doubt I have about that approach is that tampering with the heating mechanism to push temps above design specs. can lead to plastic meltdowns, and possibly a fire.
Slowing the rollers however is a different matter as it doesn't risk exceeding the device specs without added protections.
Since you raised the point I gave it some thought and even did a small LTspice sim.
It would appear that rectifying the 120VAC into DC (like a PC SMPS or cellular phone charger) and then producing a stepped replica of a sine wave using scaled PWM fed into a 220 uF or larger cap (as also found in PC SMPS units): we can have a variable frequency sinewave suitable for altering the speed of a <200mA synchronous AC motor without risk of a breakdown or fire.
The caveat here is we're dealing with the 120VAC side of things and must design appropriately.
Now to drive the sine wave PWM...a 555 chip can do it via an optocoupler into t he high voltgae FET (also found in a PC SMPS)
This is it in principle, but not exactly,as we'd need a variable freq sine wave source perhaps from 10Hz to 60hz.
Generating PWM from rectified sine wave using 555