Any chance of a picture of the recorder? I'm not sure if it's the one I'm thinking of, but I have (stashed in a dark corner, somewhere) a "three piece suite" Ferguson, comprising of recorder, tuner/timer and camera.. If it is the same machine, then the capstan definitely shouldn't be in motion until you press a function button.
Marc has it sussed.. Look for "grain of wheat" bulbs on eBay etc...
http://www.ebay.co.uk/sch/i.html?_from= ... s&_sacat=0
My granddad used a few of these to keep old Fergy/JVC machines on their feet.. They also make good panel illumination for some radio and Hi-Fi kit, as well as back lighting for car panel switches etc.. Current draw in the order of 30mA to 80mA - we used bulbs in the region of 30mA to 50mA without issue.

Certainly, if the bulb went O/C the machines would do weird things to alert the user to the fault, but I don't recall the capstan motor running constantly under this fault condition.
Marion