Something I do whenever I face a task like this is to re-evaluate the entire brake system, at the very least you should completely flush the system. I disassemble the brake lines and blow compressed air thru the lines to evaluate the flow of fluid. I have had collapsed or partially-collapsed brake lines on various vehicles over the years, and once when I bought aftermarket pads for my VMax in the 1990's, I had a set of pads which were fractionally too-thick for the caliper, the pads went in OK, and the wheel mounted, but the brake dragged. I disassembled the caliper, cleaned everything, blew-out the lines, used new fluid, and still had the problem; disassembled the caliper again, disassembled the master cyl to see if it was hanging-up (nope!) and finally decided to mike the pads. About 15 seconds of contact for total exposure to my belt sander & 120 grit solved that. Things happen.
I use my Dremel & a brass bristle brush sometimes to remove crud from the crevices if it's dirty to that extent, then a needle to make sure the small pinhole is open & unobstructed. Brake cleaner w/a wand nozzle attachment is good & I use that for the hoses, you can use it into the hose fitting of the banjos. A good air-dry w/compressed air, & time to reassemble! Don't forget to use some brake fluid on the piston seal & in the bore when reassembling! I pre fill the calipers w/fluid & position the handlebars at opposite side lock to which the master cyl is on, to have the master cyl @ it's highest point for the air bubbles to migrate up as you pump the handle. As long as you see those tiny bubbles streaming out the chamber holes, there is more air in there, so keep pumping. I have a Mity Vac & use that to bleed as well, but the final lever pumping still has to be done.
