Hi

When you view your turbine from the rear end,position the EGT probe between the 4 o`clock and 5 o`clock position. This is a good starting point,as the "Hydrostatic pressure differential" between the upper and lower halves of the combustion chamber,causes more fuel to tend to be in the lower area of the casing. The EGT probe should protrude not more than 4mm into the exhaust flow. 0,5 mm is too little and won`t achieve an accurate reading. Your ECU is tyring to control the fuel flow,according to the exh. temperature. Do a manual start and not full auto-start,so that the ECU can learn the parameters and then do a full auto-start.

The o-ring could be in a groove at the front end of the shaft tunnel. This is supposd to prevent the bearing`s outer casing from rotating in its bore. Better not having an o-ring - just better tolerances in clearances. If it has an o-ring and you cooked the engine,maybe this o-ring is damaged?

I used to use a "pull-scale" and attatch it to the compressor end,with my own nut. I pull on the scale and when the compressor wheel stops at its furthest point,I read the amount on the scale. Approximately 40 Nm. See the photo of the shaft tunnel from the JJ1800. It had broken and I`m not using an o-ring again. Just making a new shaft tunnel with better clearances.

Regards

Craig