First Tube amp build, Need a little help

I have been fiddling with this thing for about 6 months. Cant get it to quite work. So I'm systematically going through it to get the "bugs" out. Here is my first question. On my first stage preamp valve, When I look at the triode 1 which is the first valve the guitar hits, the oscope shows a clean signal after the coupling cap with a 1 meg pot. As soon as I connect the grid of the second triode to the wiper of the pot I get a reduction of the signal and some clipping of one half of the wave. Any Ideas?
 
I think we would need to know a few more details. A schematic would be useful, even if it's just hand drawn.
Are the first two triodes a 12AX7? How big is the clean signal swing that you see on the scope after the first triode? What is the biasing of the second triode?
If the second triode is a 12AX7, and has a cathode bias resistor with a bypass cap, it can only take a signal swing of about 5V between cut-off clipping and grid-current clipping. If it does go into grid-current clipping it will clip off that part of the wave.
 
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