sunk 6hp merc 2 stoke

[hydrobates pelagicus]

I guess engine about 12 years old. It was recently under salt water for 5 mins. I hosed it down, changed gear oil and it started first pull and ran in a bucket for 30 mins fine. Now it only idles with choke pulled out and idle screwed open. Runs fine in gear at speed but basically won't tick over and just dies, sounding like fuel starvation. Restarts every time with choke. I am guessing idle jet blocked with sand and I need to disconnect carb and drop the float bowl? I am technically minded with motorbikes but haven't worked on o/b before and welcome any advice before I proceed. (I did adjust the throttle stop screw which determins when the timing linkage is activated so have a tiny feeling maybe I messed up the timing maybe also? Having said that, adjusting this either way doesn't make a blind bit of difference.)