If your getting nothing to move or the unit sat for years it's likely the control valves are gummed up. Brake fluid was used and over years turns into a sanding mixture .
From the top down is the electric coil
Rubber seal
Washer
Spring
Plunger
Clips
Needle
Housing
When a control unit is electrically turn on the coil is energized pulling the plunger down against the plunger spring causing the needle to SPIN and DROP allowing the fluid to pass.
That is the reason the needle has two cut outs . 99% of the time a problem will be with the needle being stuck in the aluminum housing as the needle is steel.
When working to remove the needle which is likely frozen to the housing you can use Carb cleaner or oven heat the housing or use vise pliers, grasp the end twist and pull it out. Blow all the passages out clean the needle then while holding the housing place the needle in to see that it will fall out when you let go.( it must go in and fall out easily) Remember when the plunger is pulled down the needle MUST also fall down.
After no elect, the plunger spring pushes the needle up shutting fluid off
From the top down is the electric coil
Rubber seal
Washer
Spring
Plunger
Clips
Needle
Housing
When a control unit is electrically turn on the coil is energized pulling the plunger down against the plunger spring causing the needle to SPIN and DROP allowing the fluid to pass.
That is the reason the needle has two cut outs . 99% of the time a problem will be with the needle being stuck in the aluminum housing as the needle is steel.
When working to remove the needle which is likely frozen to the housing you can use Carb cleaner or oven heat the housing or use vise pliers, grasp the end twist and pull it out. Blow all the passages out clean the needle then while holding the housing place the needle in to see that it will fall out when you let go.( it must go in and fall out easily) Remember when the plunger is pulled down the needle MUST also fall down.
After no elect, the plunger spring pushes the needle up shutting fluid off