[Richard]

Look at the link I provided, and expand the straight on view of the priming knob in the drawings. You can read the priming instructions if you do that. Hopefully your new assembly will cure the issue.

To get you on the road, take the air supply off the tag solenoid, and cap it. You may have to go to Lowe’s/ACE/HD to get the fittings if you don’t carry them.

I don’t know the solenoid part number. It is a simple 12V activated air solenoid. When you cap it, maybe there will be part numbers on what is there.

Another work around would be to simply remove the solenoid and connect the two air lines with a quarter turn shutoff valve. You would have to manually open to lock the diff, but you would retain function if you needed during your travels this holiday season. You want to make sure you do not have air going to the air diff lock while driving on the highway, or you will have a far bigger problem on your hands.