Larry,

Depending on how it is dropping what you are describing could be normal. If the heli seems to be jumping or bobing up and down by an inch or so then it could be the flybar sticking inside the rotor head. If you are talking about the heli just seeming to slowly decend by a foot or so and then come back up then I'm afraid that is normal. The constant adjustments that are required to maintain a hover can cause one blade to drop more than the other at times and this can cause the heli to drop. Just like you are constantly making adjustments on the right stick you will constantly make adjustments on the throttle as well to maintain a stable hover. This is why a lot of people remove or lessen the ratchet in the throttle stick to make it easier to make these adjustments.

So depending on exactly what you are describing it could be some binding in the head or it could be completely normal.