Thanks for the reply and the link.

I thought I fixed the problem but it started to crop up again today. after about 3 mins of flying the heli spins and comes down. I again took out upper shaft and reinstalle. Problem fixed for a few mins then slow upper prop and spin down.

I now see that I have a chipped "tooth" on the gear that spins the lower prop/shaft. Do you think that may be my answer to my problem

Kenskid