See my Post :
8X L/MONO(TREBLE) Jack Replacement. The link is here:
: I am having a problem with the connection to the L/MONO(TREBLE) Jack on my 8X. Also, the “plug to jack” physical connection is not very tight. With the slightest tug on the cord it falls out. Both problems are very annoying to me, especially when I am playing for a group audience. I always...
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I had problems with both the L/Mono(Treble) and R/Mono(Treble) Jacks on my 8X. The fit on the Jack plug was loose in either 8X Jack and there was always intermittent electrical contact with the signal to my external speaker cutting out. This drove me nuts, especially when playing for a group. I did not like the Jacks on the 8X PC board. I think they are too "flimsy". My solution was to replace the L/Mono (Treble) Jack with a "Switchcraft Conxall Jack" that is much more substantial than the Jacks mounted on the 8X PC board. The Jack fits perfectly for a "through the hole" mount on the 8X (no drilling necessary) with a nut on either side of the 8X case to hold the jack firmly in place. I am very happy with this replacement.
If you want to do an identical replacement of the 8X PC Jack Board, get a new one, and just remove the front grill of the 8X and you will have direct access to the PC Jack board, which is easily removable. There is a wire plug connector on the PC board so no soldering is necessary. If for some reason you can't get a new 8X board, you should be able to buy a new jack (Mouser, Newark, etc.), remove the old jack from the PC board and solder a new one in.