New Thermocoupler

I bought 2 pairs of thermocoupler because my old one was giving 2,6ohm on the termistor and I have instructions from Zortrax that heater should have 15ohm while termistor 1,5ohm

Both new pairs give 15ohm and 3ohm at 15degree room temperature

Please tell me what I have to do

This morning I wanted to make some tests:
made an aluminum block where I can insert thermocoupler, termistor and my thermometer.
I have 2 old themocoupler set, one is the one that came with printer, one is the actual I’m using.
I started with the oldest and set printer to load filament option, Zortrax told it is made at 240 degrees

First I have to say my thermometer is slow in reading, when the printer beeps to insert filament (temperature reached) my thermometer is still raising, however the printer is no longer heating, there’s a temperature drop after that it will heats up again. In this phase I noted max temperatured reached by thermometer.
the oldest thermocoupler reached 230 deg
the actual 229,5 deg
one of the new ones 230 deg

you see in the picture thermometer used and over it in the back the aluminum block I made