I think your problem may be the connectors on the Solenoid expander board under the playfield. Reflow/replace the headers there & check the relay terminals for cracks/dry joins & check the female connectors too. In lamp test mode check the dedicated lamp associated with the SEB is present & flashing with the rest of the lamps. The relay should be clicking as well.

Failing that, check/replace the female connectors on the solenoid driver board J4 if they have not been replaced (good to replace anyway) as you have tried several boards so probably not male connectors. These are the solenoid data lines that come from the MPU (J4) most likely not the issue though as a J4 connector problem would usually cause erratic or wrong coils firing rather than a weak coil(s)