New gaskets isn’t a horrible idea. I suggest viton.
If your solvent is actually eating them, then you’re looking at silicone, which has no business in an LPG CLS. I’ve encountered a brand name rig that had 1/2 dozen silicone gaskets scattered throughout when it came in the door (new). So while I doubt you’re dealing with silicone, an applaud “new gaskets” and suggest you up that and get (a supply) of new nuts.
I suggest : The Death of Horatio
and at least a couple of the threads hit by Search results for 'Brass nuts' - Future4200
Imo you should also aim to ditch the 6” single pin clamps in favor of the double bolt style. Technically you’d have to do something pretty stupid to get n-butane above the rated pressure for those clamps, but I still suggest changing them.
Unfortunately, if you’re putting the solvent back into the same rusty/gunked tank that it came from, then expecting it to get cleaner makes little sense….were the material column were packed with filter media, you would expect things to improve, but without the ability to clean out the inside of the tank, you’d still never get all the way to clean solvent.
Which is a primary reason folks prefer stainless tanks with removable 6” caps.
Gauges lie. Once you understand how they work, you can appreciate why. Any over-pressurization will permanently deform the Borden tube and give you a gauge that lies.
You can also get hash in there… they make solutions for that. See : Let's see your set up! - #745 by WhereAreTheStones (actually I suggest the whole thread…especially if you’re a visual learner). There are both good and bad examples in there.
Where is that screen located? Below material column, above dump valve?
If what you’re catching is particulate from the tank. Deliberately filtering it before distillation (into a clean tank) would be ideal.
You can probably clean your current tanks (without removing the valves) if you’re determined about it. @BigM_2 might even be able to offer some tips on appropriate regimen
@GroovyOctopusLabs is correct that servicing that pump before using it is the right move.