I am not trying to push one brand over another but you need to install a co52capt drier, its sporlan. Solid core with access ports, you can check your pressures. Those bullet driers aren't even recomended by the compressor mffg's or most valve companies, they fall apart. You need to just change the cap tube along with it, it is a policy where I work. It is too cheap to ensure no blockage or wax build up. The c052capt will help to clean some of the debris, but this all came from that dirty condensor. Bottom line, that was your issue. Channge cap tube and drier and pull a good micron vacuum and you will be set.
Lol! I poured a fair amount of beads out of the dryer that were loose. They weren't crumbly at all. The rocks in my hand were in between the dryer and condenser before the dryer screen so I can't imagine that material traveling through the cap tube, evap, comp, & condenser to accumulate there. Cap tube cleared up about 6-8" up. Also it was very dry, no sign of oil whatsoever. Compressor still running quiet though. It's a 134a system and the condenser had enough wool on it to knit a sweater!
Sporlan C052capt-tt-hh drier is specificall designed for cap tube systems with wax issues. It has carbon, solid core, strainer and felt pad. Sporlan made it for these specific issues.
And sporlan does use on the normal driers, a solid core 30 micron (which does most all the filtering) then a mesh screen 40 micron and the pad that is 20 micron. The screen and the pad are just as a precaution(oveer kill).