Sorry, guys, but I need help because of Bitmain support completely useless.

With stock firmware and stock settings (537Mhz, 13 voltage) for 1&2 chain temperature is below 70C but for 3rd it's higher than 100C.
I think heatsink didn't properly place on chips.
https://www.dropbox.com/s/u8i0pkn70ks20t4/chain_3_103.png?dl=0

I tried latest Bitmain firmware and Blissz firmware - still overheating.

I tried to run it with only one 3rd chain (overheating) and got this:

Chain#   ASIC#   Frequency   GH/S(RT)   HW   Temp(PCB)   Temp(Chip)   ASIC status
3           60                537             6517.26           421        53                83   oooooooo oooooooo oooooooo oooooooo oooooooo oooooooo oooooooo oooo
Fan#   Fan1   Fan2
Speed (r/min)   5,220   5,760

So, even alone, with fans on 100%  its 83C and had 421 error during 20min test.

How do you think, guys, should I send defective chain to Bitmain for repair?
Thanks