Yes, the code is right. All voltage in the control points okay (low and high). Most likely I have overheated FETs, or they are faulty from the very beginning. Looks like they pass overvoltage - that's the reason of crazy colours distortion.
I've read a lot in internet for 2N7000 - everyone blame this piece of crap. As alternative people propose full analog BS170. What do you think of this change?