207 Fuel selector overhaul

Fuel is crucial.  Ask any pilot.  Whether you are in the air and want fuel to flow to your engine, or on fire, wanting the fuel to STOP going to the engine, a properly working selector valve is pretty important.  So when you have a working valve, it makes one nervous to take it apart and replace O-rings.  Especially when one of the most experienced guys in the shop walks up, says, "wow, you are brave!" and walks away.  But I survived, and it passed leak tests.  The real test will be when it goes in the plane, but for now, I can be happy about actually succeeding.  And having pictures.

Fuel selector, lines marked, ready for removal

cleaning with acetone.  Making sure not to erase alignment marks!

Old O-rings. I think they were originally round. The sticker on the unit had a cure date from '69. Replacement is well overdue. 

All the parts and pieces lined up, just like the picture from the manual

I don't have a picture of it all back together, but rest assured that its no longer in 14 million little pieces.  My tips for anyone attempting this act:

1. read the instructions from the manual, copy pictures, take notes, cross off steps already completed, whatever it takes to make sure you do everything in order and don't miss a step.
2. Disassemble on a tray or something to help catch little pieces.  There are 6 springs, 2 little silver balls, and countless other pieces that are easy to lose and expensive to replace.  
3. Lubricate sparingly with fuel-lube.  DC-4 is much more likely to clog stuff up, and is not as compatible with fuel.  Or so they told me. 
4. make sure you have everything lined up exactly right when you put it together. I think I had to remove and install the last roll pin about 5 times, cause something wasn't lined up right, then i forgot the washer, then something else wasn't exact, then I forgot the washer again... rest assured that it is now perfect :)