screw compressor failure

[aygul]

Hello everybody,
I have a big problem about our chiller units (water cooled evaporator, water cooled conderser and R22; screw compressors).
We have a chiller unit with water cooled condensers and the unit have 3 independent circuits with semi-hermetic screw compresors. At that moment two compressors were burnt and only one compressor is runing. One of them these burnt compressors was failure at start up , and it worked only 5 minutes. The other one was failure in five days after start up.
In attached file you can find the measurements for running compressor. Could you please give me answers of questions?

1- According to attached file, I think superheat is very low... Is there a flood back problem in the system?

2- If txv is adjusted again, can this problem be solved?

3- How can i understand oil migration? (These compressors have oil sperators)

4- Is there any other reasons for burnt compresors?

Thanks for your comments and helps.....

Regards