Well, I jumped in the deep end, and purchased a brand-new CDM4 from Sebastian at Justone in Germany - he has a good stock of new units, expensive, but reliable.

Firstly, the CDM4 laser is NOT physically compatible with the original CDM2 tray, so the tray must be reamed out as shown, to allow the larger CDM4 counterweight to rotate freely all the way, and enough so that at the opposite end, the laser can reach the TOC.

Basically there are 2 notches on the wall which must be removed, and the wall thinned slightly.

Don't hacksaw off the CDM4's counterweight - it will fit, but the balance will be shot.

Here is the top side, showing the leaded component changes by yellow arrows.

At the right side, is the 7910 -10V regulator mod, with associated capacitors, which gives much more stable current to the focus circuitry.

Here is the SMD side, showing the new components. All components installed in this conversion are Vishay BC-Philips, in keeping with the original specs.

It's reading the CD's, and I am monitoring voltages and the HF "cat's eye" waveform to see that all is working OK.

At the right edge, is the blue and white wire connected to R3102, which is adjusted to 50 +/-5mV at poti R3106.