happens when i shift into 2nd gear from 1st or 3rd, i get this sound when iam releasing the clutch almost sound like air sucking through the line/grinding , what would this be?

sometimes it'll find it hard to get into first gear, second gear, third gear, i took it to a mechanic and he don't think there seems to be anything wrong with it so he said he drove the car, didn't take anything apart, but i can tell a difference that it's harder to shift then normal and sometimes grinds, this all started after alot of rain, and isn't like it all the time, today she was shifting perfect.

maybe time for me to get under and drain the tranny and put in some GM Syncromesh???? replace the clutch?? what do you think

 

ttt