You are absolutely right re: speaker wiring causing the overheating. Disconnected one part and it stayed cool for a few hours. Will re-connect using the instructions above.
Re: light bulb. Would these do?
https://www.ebay.com.au/itm/6v-Festo...0AAOSwt5hYicnM
Or these?
https://www.ebay.com.au/itm/6v-Festo....c100005.m1851
Would also be happy to change to LED strip if not too complicated? I think I have one lying around somewhere
Cheers
James