X-rite 408 densitometer different readings

Hello everyone,

Hope you can guide me to the correct tread or help me here.

I've been using a gretag densitometer and it gives readings similar to:

1.45 m
1.35 c
1.1 y
1.8 k

With those readings i get pretty much the result we need but i just got a used x-rite 408 and gives very diferent readings:

1.75 m
1.7 c
1.24 y
1.3 k

I tried the quick calibration and did not change much. I then tried tu buy a reference card but i don't know whether this unit is polarized or non-polarized so i ended up with two main questions:

1 Is there a way i can tell whether if it is polarized or non?
2 is this a common fault to densitometers and may be fixed by the long calibration or it might need service or repair?

Any help appreciated

Moe