...put sand in the sear, very rough and must be 5 # pull!
Never cleaning is EXACTLY like putting sand in the moving parts!
My (used) mk2 Standard arrived filthy - just like the OP's. After giving it a complete takedown and cleaning, I discovered that the grime had caused and masked excessive wear. The sear and bushing were both shot.
The pistol had a variable trigger pull. If you cycled the bolt and pulled the trigger, the pull was over 4 pounds. If you cocked it, put the safety on and pulled the trigger, then took the safety off, the trigger pull dropped to about 2.5 pounds. This was due to the wallowed out sear hole. Volquartsen sear to the rescue! Very consistent 2.2 pound pull after replacement.
Next thing I found was my trigger pull consisted of takeup|pre-creep|creep|break. Pre-creep is after the trigger bar has engaged the sear and before the sear begins to slip out of the hammer notch. This is actually the hammer being moved forward to take up slop around the worn out bushing and the slop inside bushing around the hammer pin. New Clark pin & bushing set to the rescue! No detectable pre-creep after replacement.
Then onto the trigger itself. AFAIK, fixed sight models (Standards) had no adjustment screws while the adjustable sight models (Targets) did have a screw to adjust the overtravel.
My overtravel was quite good and didn't need reduced, but my pretravel was a mile long. My mk3 has a VQ trigger installed, and I found that it never needs adjusted once it is set. So I decided to pin out the pretravel in my mk2 and save some $$. I also like the looks and feel of the Ruger trigger better than the VQ trigger. Here's a couple pics of the pinned trigger.