That is an unbelievable amount of bad luck,, in the last 25 years or so since Hitecs have been around, I've only had one Hitec servo fail in flight, luckily it was a flap servo and I was able to land the plane OK.

I question what kind of punishment you're putting those servos through, to have 6 fail in such a short time? to small for the job? over voltage? gotta be something

good luck