One bit of advice is to buy a hand pallet truck, I bought one off eBay for about £35. You also need a strong pallet the size of the subframe. It make the job so much easier than trying to wheel the subframe out on the road wheels. When it comes to reinstalling you find it ridiculously easy.
.....which is approximately 17.59754 UK fluid ounces for the English-speaking audience..... [/attachment]
<<<snip>>>Check your electrical connections and earthing, apply 12volts directly to the horn and see if it actually still works before getting anymore complicated