Crystal Drive... Has anyone had this build Oscillate like crazy??

[gwyador]

I built up a "crystal drive" that has a couple of MPSA18 transistors but for some reason it oscillates (squeals) like crazy and the pitch changes no matter which knob I turn. I am currently using the current build documents. has anyone else had this issue with oscillation? If I run my guitar through a buffer and then into the crystal drive the oscillation goes away... so I have to suspect it is caused by loading on the input circuit... I see their are some mods for this circuit that mostly change the impedance of the input... but I did not get that it was because of oscillation... does anyone have thoughts on this? just curious...