Can't get homebuilt Boka working

[PIDnerd]

I'm jsut about to say to h%ll with building a still, but maybe someone can identify the problem(s). Mine is that I don't know what I don't know...
The still: 2" copper pipe, about 5 feet high. Starting from the top: internal single coil condenser with about 12 turns of 1/4" copper tubing. Coil ends come through the top. Also a 3/8" hole for a RTD temp probe. One copper plate slanting up 13 inches from the top. Another plate slanting down on the other side about 2 inches below the first. 1/4" copper takeoff soldered just at the lower plate bottom which curves down 90 degrees. Temp probe tube soldered between the plates. 1/4" needle valve 3" below the plate going to a 18 inch Leibig condenser (3/4" copper w/ 1/4" inside.
Column is packed with 6 rolls of copper mesh 5" wide and 2 feet long. Packing stops 4" below lower plate and 4" above the triclover fitting for boiler.
Heat manually controlled with a PID controller cycling a solid state relay with a 20 second duty cycle.
Coolant is gravity fed from a bucket hung from a joist. Flow is from bucket to lower Leibig condenser inlet, upper outlet tubing to top condenser input. Output of top condenser tubed to floor level drain. 1/4" needle valve between upper Liebig outlet and top condenser inlet.
Temps are measured between the plates and top condenser.
Boiler is a Milehi milk can with a 1500W immersion heater.

Operation: Heat @ 100% until alarm actuates @ 145 degrees. Coolant flow started by sucking water to fill the system, then gravity takes over. Open output valve for 5-8 drops/sec when top temp reaches 150 degrees. Then, try to control to top temp by adjusting coolant flow. Still will not stabilize - temps vary from 150 to 185. Nothing I've tried (reducing heat, adjusting output, controlling to plate temp) has any effect. Alcohol % is erratic. I've gotten a quart @ 85%, than 70, then 45, then 20. Today the first was 45% and lower from then on.

I've read every post about build and operation here and in several books, but am clearly missing something. Whatever fun this activity seemed to offer is gone. It isn't worth my time to battle unknown problems. But before throwing in the towel and buying a column, thought I'd give it one more shot on this forum. Hate to be defeated by something so many others apparently succeed at.
Thanks for reading - any thoughts welcome.