Are you sure that’s a HVLP gun?
The manual seems to say it’s a conventional gun, although there is a discrepancy on air consumption between your box and the manual I found online.
Try some primer through it when you’re ready and see how you get on as it has a 1.8mm tip.
Re-Nu on murdock road might test the motor or the vfd too.
I just wandered in their workshop (couldn’t really find a reception type door) and asked about them about looking at a 3 phase motor with no plate on and they seemed helpful. I havent got round to going back yet.
using a swept 90 would certainly put less strain on the input air line.
if you unplug the airline the filter won’t be pressurised would it? enabling changing the silica and draining the dropout.
if you have the inclination you could make a small mod to the front roller.
Take the rollers off and add two small ones either end.
If you don’t want to drill and pin outer rollers a pice of blue water pipe or similar will keep the rollers apart just to try it out.