Is your steering wheel the wood one or the leather wrapped?
Reason I am asking is that on my 69 Grande I have the rim blow with the wrap.When I installed my "first" switch, I cleaned out all the old rubber and whatever in the side channels where the switch is suppose to slip into.After making sure there was nothing in there I proceeded to instal the switch. When I hoked up the battery again, the horn blew continuously. I had somewhere bent the copper band inside the switch so that is was making contact.Once this happens the switch is history.
Second try with another new switch I took a dremel and made the channel larger so that it was easier to instal the switch, I put in a little contact cement to hold it in place and that one is working fine. What I did was made the whole channel wider so I did not have to force the switch into the grooves on either side, also made the grooves bigger. I do not know if these switches are a bit heavier or larger than the old ones but they are deffinetly a pain to get into the grooves without bending the switch. .