some rattle crow problem

[Gila_Crisis]

last time i got a problem with a non working rattle crow (see it here http://www.diystompboxes.com/smfforum/index.php?topic=50723.0 it was a reversed diode, problem fixed)
now it work, it's a cool one!!! really like it.
here some photos of the circuit:



now the problem is another one. on some setting (about with the sens knob set from half a way to the max) the pedal is start wisteling or it' like a little dog that bark, and some times it does it all alone like it's selfoscillating and without touching a string! the only thiing to avoid this is to put the freq knok all the way up.
it don't know but i suppose there's something wrong with some condenstors. they look like this:

this are two .47uF and one 1uF
on them is written:
+,47
+35V

here them schem:
http://users.rio.com/senorris/junk/CrowSchematic.gif

[Gila_Crisis]

oops... do you think i putted in some .47uF instead of the .047uf?!?

[Gila_Crisis]

i founded a thing more, thore blu condensators are electrolitic tantalium!!!! oooops.... i remplaced the two .47uf with a .047uF. but now i'm gonna remplece the 1uF as well.
what a shit figure.... i didn't know they were electrolitics........