This is the bit of circuitry you need to look at - on the
F-2835 MM Head Amp, note that the connections to VR03 & VR05 are through the ribbon cable. Leave the JFETs alone, they can look after themselves.
Note well that TR105 and TR101 (the top 2) are
NPN, and that TR107 and TR103 (the bottom 2) are
PNP - if you changed these transistors, check what you used. These transistors comprise a kind of regul
ator called a capacitance multiplier - you should have around +11V on pin107 and -11V on pin113, each adjustable with the respective trimmer.
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