Bob S,

Welcome to the Stovebolt.

Your profile doesn't indicate what year rig you are working on, but the book shows the plastic encased spring is used from '47-'57. If that spring tries to carry too much current, it will heat up just like the coils in a toaster. Is there a horn relay that has been bypassed or rewired incorrectly by someone. The circuit up the column for the horn button shouldn't carry much current at all...just what the tiny coil in a horn relay requires to close.

Stuart