I've got a pair of 2006 BF150's with 1800 hours and one of them recently started running rough and dropping rpms at speed. Dipstick shows water intrusion and cylinder 3 spark plug is rust colored. Compression test reads 205-195-175-200. Prepared to do a leakdown, but is that really going to tell me anything I don't already know? I'm assuming I've got a blown head gasket or corroded head and in either case, I've been advised that it's really not worth repairing by a long-time Honda mechanic. Really not wanting to repower now, but I don't want to waste my time and effort chasing a lost cause. Could this be anything other than gasket or head corrosion? Is one more likely than the other? If head gasket, how many have had success just slapping another gasket on and sending it (not going to put anymore $$ into than that)? Thanks!