yeah, I agree your voltages are spot on...

what pinion are you running with all that extra weight?

Also you might need to lube up the heli with 35 flights on it if you haven't done that already. Check for wire shorts in both the main motor and the tail motor also.

How long are your flight times anyway? And is it with the stock 800mAh pack? How hot is the main motor getting when you set it down?

Those are just a few of the ideas I have