Vintage Synth Repair

hey, i just got a siel dk-600 which i am excited about. it's different
than the older synths i've been working on but i thought i'd see if
anyone else has any experience trouble shooting these. 

problems:

it powers up but there's no sound and no response form the
buttons/nobs. one of the LEDs is burned out too. i'm hoping that since
all the nobs and buttons are non-functional that there is some master
routing for the controls that has gone bad. any ideas? how about led
replacements? 

thanks for all your help guys!
-johnny