"Sold as Seen" means exactly fuck all!

"Sale of Good Act 1982 - Goods must be fit for the purpose for which they are sold." This goes for second hand items as well as new. Get the dealer to sort it to your satisfaction or get it sorted and drag their sorry arses to the small claims court

Mind you before ripping the guy a new arsehole you really need to give them the opertunity to rectify the problem(s)