Strange sim not accepted

Hi,
I have strange sim not accepted in nokia 3310. Sometimes it show sim not accepted but sometimes not,no network. RSSI is 147. I already changed cobba amny times and reflashed mcu+ppm+eeprom with different versions. Also try Noktool18 by rolis for unlocking and faid. I also reflowed ccont.
Still same sim not accepted. How to repair?
Thanks for attention.

i'm going to change my spare 3210 to 3310 with problems with sim-card.
it will sometimes accept sim, sometimes (usually) not.

i hope that this phone only has to be cleaned.

but, every hardware/software recommendations ae welcome.
i want to get it fixed when i get it.

just change flash ic or for 3210 change eeprom only 100% working