Problems with stereo, my system is being difficult again... Options

[6gsillyca]

alright, here goes.

the last few months ive been getting a lot of trouble out of my system. first the amp ground came loose so my subs didnt work properly. i fixed it. now their acting up again. i was going to go with some 0/1 guage wire to ground my amp but the hole for wire on my amp, is only big enough for 4 guage. even with just 4 guage the wire is stuffed in there pretty good. so it looks like i can only put 4 guage into my amp....

now im having problems with my cap. in my profile there is a pic of my box. me n my friend built it. the box is 3/4" board (i believe) with 1/2" lexan top. bottom is fiberglassed (where cap is being held). there are a few small holes in the back of the box to run the wires out. box is more or less sealed, the holes in the back for the wires to run out are probably acting as a port somewhat.

my cap fell apart. it is the stinger chrome one with the digital display. the top part fell off (the plastic "cap", the terminals under the "cap", the digital display...their all sliding around in my box, and just the chrome cylinder with nothing on top is bolted down to the fiberglass mount) problem is im guessing, is that there is too much pressure in the box for the cap, and the subs hit it pressureizes/depressureizes the air in the box, and the cap can't handle it.

can someone please verify if this is possible and if this might be happening.