Hello. I've lately been having difficultys with my MG50DFX Marshall amp. The problem is, is that the input jack will refuse to make a connection unless I hold the quarter inch jack up. I don't know much about amps and I'm hoping this is a simple fix. I've already taken the amp's motherboard out from the cabinet and taken the piece of plastic off of the top of the jack. I've attempted to bend the 2 metal pieces that make a connection to the male jack down, but to no avail. It still refuses to make sound without me holding the wire up; otherwise, it'll just make feedback. Any ideas?