I have a HF blast cabinet and like every other one they produced mine leaked quiet a bit. I did some Google research and found many ways of upgrading these HF cabinets.
In the end I completely dismantled mine then, reassembled it with silicon in between the cabinet pieces. I also upgraded the gun and pick-up tube. Installed LED strip lighting, a small shop vac with a Dust Deputy, added an air dryer, and regulator.
It probably took 6 hours and cost me $300. It works great for me now.
My $.02


Curt Warren
Salt Lake City
1948 1.5ton Loadmaster
http://photobucket.com/48loadmaster