[LEAKYSEALS951]

There are a bunch of sandblasting cabinet videos on youtube, including modifications.

Several common themes I've seen with the sandblasting cabinets videos / threads are to put a whole bunch of air dryers in line to keep the air as dry as possible (like three or four in a row). Also, a lot of cabinet users remake the intake/air metering/mixing valve to get better mixing.
You could certainly experiment with media levels, but you've got a clogging issue. It might be better to sort that out first. Adding more sand just makes a bigger mess to go through while sorting things out.

Also, pay attention to media. Make sure you aren't using playground sand. It collects moisture, has uneven grit size, and will clog. Invest in good media.

Also, you are on the low end of cfm rates. This is a factor (at least with the external sandblasting tanks- I have no experience with the cabinets). The HF freight units will list a range (such as 12-16 cfm), but that doesnt mean it works well at 12. With the regular sandblasting units, it might barely work, and might be a pia. Your compressor might provide the minimum at 90 psi for a couple of seconds (it won't work well @11.3 cfm), but will quickly drop to sub 90 psi, which will promote clogging (won't work at all). I would recommend sistering another compressor to get the cfm/pressure up.

From what I have read (others who have had frustrations like you describe), you kind of need to address all of these to get a consistent result.

Good luck