Nikon SB-28 Speedlight Repair

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I got a like-new Nikon SB-28 Speedlght from ebay. As is the case many times, the item has hidden faults.

In this case, the mechanism to activate the 20mm and 18mm settings was faulty. To be more specific, when the diffusor screen is pulled out, the LCD screen should show 20mm or 18mm, but in the case of this flash the "Zoom" indicator stays at the last setting. That would be 24mm as the widest.

So the little switch in the head may be faulty and may need to be cleaned.

Here is the flash:
 
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Remove the rubber end caps. Looks like someone was tried this as the rubber caps were held on with contact cement. However, it also looks like they never took the screws out. This is good news, as it indicates the flash has never been tampered.
The two holes go to the capacitor, to allow one to discharge it.

 
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These 4 screws were initially still covered with the two-sided tape, so they had never been removed. That is a very good finding.
 
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After taking the flash head apart, the flash tube/zoom assembly needs to be removed from the top of the flash head. There are two screws to remove.

 
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Under this piece of tape is the switch assembly that activates the 18mm/20mm settings when the diffuser is pulled out. Diffuser is on the other side of this panel.

 
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This rubber nipple was installed wrong, it was permanently puckered in; making continuous contact. It popped out and sprang back to its natural form. That fixed the problem.
 
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As you can see, there was nothing wrong with the contacts; nothing to clean here. The issue was only the rubber nipple being deformed and in continuous contact.
 
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All I had to do was carefully re-assemble it, making sure the rubber nipple did not pop out of place as I installed the screw. I suspect that was the issue during assembly back in China. This is kind of a three-handed job, as I needed to keep continuous pressure on the switch assembly to keep the rubber nipple from coming out of its hole and distorting when the screw is tightened. I have the diffuser pulled out so the nipple is extended and not making internal contact.
 
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Re-assembled and all functions are working now.
 
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Prior to disassembling this flash, I disassembled my old beat-up SB-28, as a dry run. During that affair I noticed the old SB-28's flash tube was covered with some crusty material as weak flash tubes I have replaced in the past looked normal.
Anyway, if I need another project I might replace that flash tube. The capacitor in that old one also leaks a little, even after 're-forming.' So a capacitor replacement might be in order too. I can locate a source of the flash tube but not the capacitor at this time.
 
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