The Tech forks have some advantages over the excellent Marzocchis that came on my OSSAs. For one thing, they are still being manufactured! The Techs are much easier to work on. They have no propensity to shoot a geyser in your eye when bleeding the cartridges. And, the bottom-out adjustment is nice – assuming I can get it to work. Plus, a design using a single spring is very tolerant of fork tube height discrepancies during installation. They are probably lighter, too.
Unfortunately, it's winter where I live so I won't get a chance to do any testing for a while.
Although I could attribute the poor bottoming performance to the very dirty (high viscosity) oil, it's possible the air spring is too stiff even though the left side had a lower oil volume than standard.
My suspension guru reminded me to leave the air volume large. I kept the air gap at 144mm on the left side and increased it to 89mm on the right side. It's far easier to add fluid than to remove it. While the fork is on the bike just by unscrewing the cap, I can use a syringe to add fluid.
Changing the fork oil level on the right side requires 0.66cc / millimeter change in level. On the left side, it is 0.74cc / millimeter.
I'm a bit puzzled about the oil viscosity on the right side being more than that of the virgin 5-weight. Usually, I think of oil shearing down (losing viscosity with use). But I guess it's equally possible that contamination will increase the viscosity.
I'm also considering polishing the OD of the fork spring so that it slides easier inside the fork tube. This should help keep the fluid cleaner as well. But I'm not sure if I'll want to use a softer spring and would prefer not to go to that much trouble. So I did 50% of the job with 10% of the work by running the spring against a wire wheel.