Goldmund Studio PL5 or PL6

Hello Everyone,

This is my first post here so for starters I would just like to introduce myself.
My name is Bryan and I am an electronics technician by means of an ancient degree and have had the great fortune of allowing my career to follow my passion for music, my intrigue by audio and recording equipment and an early interest in electronics to all come together. I think everyone should be so lucky as to be able to follow a hobby into their career.
Along the way I have gained a bit of valuable knowledge and experience in these areas so hopefully I can become not only a friend to many of you, but also a helpful resource and an interesting member of this forum as well. I prefer to not be judgmental or jaded in my opinions as experience has shown me that anything is possible in this world, no two paths are the same, and what you think you know today may be proven wrong tomorrow. With that being said I prefer to keep an open mind and always try to think outside the box and to show respect to everyone's opinions.
As you can see, I have sold some very nice gear here on Audiogon in the past and my excellent feedback shows my dedication to my selling reputation. But my reason for this post is not to sell anything but rather to reach out for help with a challenging project I have started.
So here is my challenge and project at hand. In a recent road trip and audio-goodies treasure hunt I was the lucky finder of an early Goldmund Studio turntable with a T3 tangential arm in pretty ratty shape. However, the cables, platter motor power supply and most importantly, the PL5 Servo unit had all been lost in transit some time ago when the unit was shipped from California to South Carolina. Well to make a long story short, Goldmund has been fantastic with regard to support but I am now faced with the challenge of building, from scratch, the PL5 servo unit as they of course are long ago gone. I have already successfully repaired the Papst platter motor and built a nice fully regulated 24VDC power supply for it so if any members on here need assistance with your non-functioning Papst motors I may be able to help you out with that. So with the platter motor all being in place its now time to move on to the challenge of the arm servo unit. Goldmund provided me a copy of a basic hand-drawn schematic of a PL-6 servo unit that could be adapted to drive the T3 arm but unfortunately there are major differences between the PL5 and PL6 and there are some details in the PL6 schematic that are a mystery. The schematic shows IC4 and IC6 as "boxes" in the schematic that do not conform to standard schematic symbols so an educated guess is the best I can do to identify these devices. IC6 is obviously a voltage regulator as evidenced by its three connections, one being power in, one ground and the other I assume VCC for all the other ICs, but to guess that its a 15VDC regulator could only be my best assumption. IC4 is a real mystery though. The schematic shows two logic inputs to the drawn box, three leads that are directly strapped to VCC, one lead tied to VCC through a resistor and that lead coupled to another lead of the device through a capacitor. The output of the box feeds two paralleled inverters.
If anyone has the PL5 schematic, that would be very helpful because the PL5 servo is obviously a very different design than the PL6 and other than the two drive motors, an opto sensor and a few LEDs mounted in the T3 arm, everything else is a completely different layout. Also, if anyone would be willing to open the top cover of their PL6 and snap a shot of the board, that would be very helpful too as I could simply read the IC numbers right off the top of the chips.

Thanks Everyone
Bryan