[sundrop]

Might need to have the shift cable re-adjusted or replaced.. Sounds like it isnt setting firmly in gear at first... If you have a manual it is a simple thing to adjust the cable. If it is the shift rod itself that is a bit more involved... For now just make sure you have RPM as low as you can before you drop it in gear and do do any sudden forward-reverse shifts of it can chip the gears..

 

[sundrop]

The gears are cut to allow for a certain amount of slippage before they engage as it helps to synchronize them before they mesh. But alot, or a long period of grind is bad... When in doubt, have it checked out!