NOTE: opening your knife will void the warranty. Do not proceed unless you are comfortable handing small fiddly parts that cannot be replaced if lost.
My new-to-me Ultratech had a heavy and somewhat rough action (especially on opening), so I decided to try improving the action. I used a
triangle bit from Amazon, sold by BladeHQ, and this disassembly video:
https://www.youtube.com/watch?v=SKwAQE8GAX0
It's important to keep the tool perfectly vertical so you don't bugger the aluminum surrounding the screws.
Note how the angled "disconnector" at the rear of the slider interfaces with the rear sear. This is what affects the smoothness of the opening action.
Here is the rear "disco" circled in red:
Attachment 84033
The rear disco was very roughly machined.
I polished it with a rotary tool, so machining marks are just barely visible.
Attachment 84034
Reassembly was easy because I did not remove the sears. The action was noticeably improved! Note: do not overtighten the screws. There was some residual Loctite on the threads, so I just left it and reinstalled.