HI While restoring my Philco console, I ended up with two M4 Phonographs. one was restored, and put back in the philco. This is neat The other M4 had no motor, and no cartridge, after cannibalizing it for parts for the other one, So I decided to try an experiment with it.(if I destroyed it, I would still have the other one) My Goal, was to convert the parts M4(78 RPM only) to three speed operation, a modern cartridge, While still looking original as possible. Digging around my parts bin, I found a old modern type three speed phono. I measured the idler wheel, and motor shafts, and sure enough, they were the same size. I removed it's motor _base_ and idler wheel(with the three speed shifter), and installed it in the _base_ of the M4, making sure that the idler wheel was in the same place as the original one was. The _base_ was smaller, So I used large clamping washers to install it in the M4's _base_. The M4 had a string coming from the off switch, that pulled the idler in neutral when the phono was off. the replacement motor _base_ had this feature too, It was only a simple matter of hooking up the string. I installed the turntable wheel, and powered up the motor.......it worked in the 78,45 and 33 positions. Great. I now had to figure out where to put the speed selector, I settled for a pull wire with a knob that came out of the back of the phono. Once you install  the unit in the cabinet, you will never see it. The next step, was installing a modern needle pickup, with a flip type needle. next came the balancing act of getting the proper pressure on the needle. The M4 record changer, is made for 10 or 12 records. It just so happens that most 33 RPM records are 12 and the record changer works perfectly with LP's!  I hooked the modified M4 to a amplifier, and played a 33 RPM LP............it worked perfectly. I next played a 45 RPM, them a 78..........no problems. The only negative thing is. the auto changer will not work for 45's. I fear that I have installed the wrong impedance pickup though, I hooked the phono to the 48-1270, and I doesn't have enough volume. I could use some advice in this area. I know it's not the radio amp, because the original phono, with it's pickup is plenty loud. I am almost certain that this could be applied to other phono's of this era Andy Taylor