Vintage Synth Repair

I need a service manual...

the gnat has a dead keyboard
Is triggering just one time, when is turned on (and not on every key).

all the functions seems to be correct: vco, lfo, vcf, ar (yes i was
able
to test it...)

Is just missing the (I think) keyboard scanning functionality and the
trig
(or gate) from the keyboard.
+ i think the decoding of the keyboard is wrong too (I press C  but i
get
every time e different note).

thank you for your help
at