Bongo Fury

hi,
just hoping someone could give some advice on where to start 'fault finding' procedures please.
The wheel has been changed at some stage to a wooden one.
When I last used it, it gave a faint 'whimper' and died never to be heard again....
Any advice greatly appreciated
thanks

Check wires at horn for 12v using a multimeter.
If 12v are there, new horn needed.
Easiest place to start.
Or fuse first