This bulb I took out is tiny & I didn't find a replacement; all the illuminated door pushes I found are 12V max. I've ordered the relay now but if that doesn't work I'll look harder at changing the bulb.
I'm not sure my soldering skills are up to fitting an LED, it's pretty tiny. So first off I've decided to try fitting a relay switch. If that works the door press will be illuminated again on a 12V circuit which and that'll actuate the relay to close a 24V circuit through the bell. Fingers crossed.
Thanks for the suggestions so far. It's a "MOTORISED white BELL (152mm/6inches) FULLEON CFB6D24 BELL, 18/30VDC, 152MM (V)" sounds like a school bell or fire alarm going off!!!!
Now I've taken the lamp out all the button is doing is complete the circuit. Before that the lamp was in parallel...
I wanted a louder doorbell and the one I got can now be heard anywhere in the house. Its 24V which needed a new transformer and I found the bell rang continuously until I removed the bulb from the illuminated doorbell button as it was being overpowered by the higher voltage.
The problem now is...