I think they are 501 bulb 12v 5W T10.
I tried changing mine for white led's but they would not switch on.
I tried turning them around but still no light so put the bulbs back in.
Not sure if I needed led's with built in resistors.
But watched a program some years ago which pointed out that the led's generate a lot of heat from the led.
And I didn't want to melt the housing. To replace its very expensive....