1990 70 HP Yamaha outboard. Had a throttle alarm late last year and I replaced the impeller. Alarm stopped. Took boat out of storage and got no pee stream but no alarm! I cleaned the pee hole and get a great stream but the alarm won't shut off or let me open up the throttle. I pulled lower end and impeller was as it should be - brand new. I greased the plate, reinstalled the impeller and I get a great pee stream but the alarm won't go off nor can I throttle up. Any ideas???