I have recently replaced the scale & meter lamps on an old Akai. On this unit there were 4 lamps in parallel, all fed at AC from a dedicated secondary winding on the mains transformer. There MIGHT be a fuse on this supply in your unit, so investigate this before doing too much.
This seems to be a common arrangement, so you could try doing what I did:-
1) Measure the AC voltage across the bulbs.
2) If you still have a good bulb, measure the current comsumption.
3) Measure physical dims of bulb,
4) Search the RS Components website to find out what is available.
I'm not suggesting you buy your bulbs from RS (although I did), merely to use them as a 'database' to help you identify the correct type/spec you require. Make sure you pick a bulb whose voltage rating is 20 to 30% higher than you measure, otherwise they will be far too bright and will burn out quickly.
While probing around inside your unit be aware that there are probably bare terminals at mains voltage, so watch out. Also, if you do attempt 2), don't try to unsolder your good bulb, as the heat may kill it. Cut one wire close to the bulb, but leave enough to re-connect your replacement. Also, one end of the bulb supply circuit might be tied to earth, so make sure you don't let anything touch the chassis while doing any testing. If you don't have a good bulb take a guess based on what is available in the correct size/style - unlikely it will ever be more than 2 watts.
Finally, don't get your new bulbs too hot while soldering them, as I found out the hard way! Maybe buy a few extra just in case. Keep the heat to a minimum and work quickly - attach the lead to the body/side where the filament emerges - you will see a solder blob there already.