Fellow AK'er dgwojo is the 'go to' person who can hook you up with new bulbs for that. Just sent him a PM or visit his website:
http://www.dgwojo.com/
He's always come through for me on bulbs, lamps, etc. :yes:
Looks light it is a single bulb, 8 volts .3 amps ( or 300 milliamps)
Might I also suggest that you download (free) the Service Manual for it as well as the Owners/User Manual from this place (just sign up):
http://www.hifiengine.com/library/kenwood/ka-6100.shtml