Trickle of Cold Water Pioneer Bathtub Faucet

egawrons

I purchased a 10 year old condo that has a Pioneer single lever bathtub/shower faucet. The faucet provides a trickle of cold water flow and full flow of hot water. I changed the ceramic disc cartridge and there was no change. I took out the pressure balance spool and it was frozen - cleaned it up and it clicks when shook - put back in faucet and still no change. Removed the disc cartrige and flushed the valve - high hot water flow rate, slow cold water trickle. Removed the balance spool and replaced just the cap - flushed using the inernal valves and got full flow from both hot and cold water this time. Replaced disc cartridge with just the spool cap (without the spool) got plenty of nice warm water flow but the lever could not control hot or cold - just was mixed warm water. Put the pressure balance spool back without the center "plunger" part of the spool and still just a good flow of warm water with the lever not controlling cold or hot. So now that I confirmed that going into the valve was a good flow of hot and cold water, plus had flushed out the valve - put the complete pressure balance spool back in, made sure both internal valves were fully open, the disc cartridege was in place - tested and still only hade a trickle of cold water and full flow of hot water. Then purchased a new pressure balance spool, replaced it along with a new disc cartridge but still no change - trickle cold and full flow hot. I have changed every part that can be changed and flushed the valve getting good flow from hot and cold during the flush. Any ideas what the problem could be and what I can try next?