From Port Lines Hobbies



Unplug the transformer!

First remove the 2 metal handles, and the bulb caps and bulbs.
Next remove the nut on top that secures the on/off switch (if it has one) to the case.
Then remove the rear plate (2 screws).
Tip the unit upside down, and remove the 4 screws that hold the base to the case.
You can now lift and tip the case out of the way, being careful not to break any wires, or bend any of the copper throttle parts.
Clean the top of the coil with a little Electronic Contact Cleaner on a tissue. This will remove most of the old carbon residue.

Inspect the cord for breaks or cracks. Replace if necessary, but be sure the connections are safely insulated, and don't forget the cord washer for the back panel, and a knot in the cord for location behind the washer.

The old rollers are probably secured with short peened rivets.
Snip the tip with cutters, and remove/discard the old pins and rollers.
Insert a new roller, and secure it with the small rivet which I supply with the roller. 
Squeeze the tip of the pin with pliers. This should secure it in place and prevent it from backing out.

Repeat with the 2nd roller, if there are two.

Re-assemble, first lowering the case downward onto the coil, and making sure that the roller assemblies engage the control levers on the knobs.

If this is a dual control unit, lock the handles down, and rotate both handles so that the rollers just barely pass each other over the coil. Look closely to be sure the rivets don't touch, because if they do, they will short against each other.  Correct if necessary.

Then, before replacing all the base screws, make sure that the rollers contact the coil when the handles are locked down, but do not touch the coils when the handles are lifted.  If necessary, you may have to slightly bend the copper arms to which the rollers are attached…..but be gentle doing so (they can snap).

Once you have proper adjustment, complete the reassembly.

PARTS AVAILABILITY: You should be able to locate all parts referenced in this clinic in our online AF PARTS CATALOG, under TRANSFORMERS.