This is similar to what I did on my BSD. Someone found a RadioShack 18v motor that fits but the speed wasn't correct. It was about twice as fast as the original So, I adjusted the speed of the motor by adjusting the voltage to the motor. My potentiometer wasn't big enough to use in parallel for voltage control (current control for torque, voltage control for speed) and putting it in series for current control does work but if you torque control the motor, it speeds up and slows down depending on the load. I ended up doing the ghetto thing of soldering like 6 3A diodes in series to step the voltage down to speed control the motor to match how fast it should be based on the papa videos. The diodes where the only thing I had on hand that would do the job. They sell boards on ebay for $5 dollars that provide variable speed control for dc motors. I'll probably put in one of those if I ever sell the machine so it doesn't look so ghetto. You found the exact copy but with a pwm board, you could easily use "non-pinball" motors and not even have to find an exact copy I would guess for most applications. Probably, the trickest part would be just slipping on and locktiting the old cog to the new motor's shaft.

ebay.com link: PWM 12V 40V DC Electric Pump Motor Speed Controller Stepless 10 100 10A

ebay.com link: 12V 24V 3A DC Motor Speed Control PWM HHO RC Controller

ebay.com link: Adjustable Regulator Pulse Width PWM DC Motor Speed Controller Switch 6V 28V 3A