540 FGZ got stuck in the hot shoe this evening. I put the flash on to take a quick picture at home. I've put the flash on and taken it off hundreds of times. I've heard reports from others of Pentax flashes getting stuck, so I always regarded it as a tricky connection and I've got a careful way of doing it that I use every time. Never mind my good habits. It got stuck any way. And of course this happened completely without warning. I'm glad this happened at home and not while I was working.
This is a post mortem describing what I did.
SERIOUS WARNING. I do not recommend the following course of action. It would be quite easy to wreck the flash and/or the hot shoe on the camera doing this. If you think you want to put any of this info to use yourself, you do so at your own risk.
Pleading didn't work for me
I tried for an hour to coax it out gently. Tried turning the camera upside down. Tried pushing the flash back in, tightening the lock, unlocking and trying again. Nothing worked.
Searched here and found this thread:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/6874-flash-totally-stuck-hotshoe.html
Ended up taking the bottom off of the flash by removing the four screws that hold the base of the unit to the body. Boy, that's a pain! I have a set of computer-repair screw drivers. I wish they had much longer handles; would have made it much easier to remove the screws while the base was stuck on the camera.
Inside the flash
Once inside the flash unit, I used a needle-nose pliars carefully to remove the plug that connects the base to the body of the flash unit. It took me a minute of staring at the insides of the base to get a clue what the problem was, but eventually I saw the long pin. There's an upside-down L-shaped metal piece that comes up from the inside bottom of the unit and ends in an O shape that fits over the top of the long pin and seems designed to hold that pin in place. The pin itself has a tiny spring wrapped around it. The pin also has a little plastic piece - sort of an arm - hanging on to it. The arm serves in part to keep the pin from simply falling out the bottom of the unit when the unit is off the camera, but the arm also takes pressure created by the spring and pushes the pin DOWN, so it extends further on the outside bottom of the unit when you slide it into its hole.
The metal piece that ends in the O and fits over the top of the long pin was not quite in what I assume is its proper place over the top of the pin. I don't know how that happened. I can only guess that, as I put the unit on and took it off over and over, the locking pin (the long pin) kept getting stressed a bit and caused this holding piece to get bent a bit. It seemed to me that because this piece was out of place, the locking pin could NOT retract properly.
Problem solved, I hope
To solve my problem - remember, at this point the base of the flash was still stuck on the camera - I pushed the L-shaped metal thingy up and off the long pin. When I did this, the spring popped up in the air. I still don't know where it went. I then pulled the pin out. End of problem - I was now able to pull the base out of the hot shoe.
I plugged the base of the unit back into the body and put the unit back together, putting the four small screws back in place.
I left the long locking pin OUT. I've now mounted the flash in the hot shoe, taken pictures, removed it, and I've done it several times. I assume that the engineers felt that the locking pin was important or it would not be there. But as far as I can tell from my quick tests, the flash unit works as expected without the locking pin. The locking pin doesn't have anything to do with movement of data from the flash to the camera and back, it's just a locking pin. The flash seems to be as securely mounted in the hot shoe as it was before. And I don't expect to have another problem removing it.
My evaluation of the flash - and the problem
I've said here before that the Pentax flash units are the weakest part of the Pentax system, for a photographer who shoots weddings and other events and absolutely needs good, reliable flash. This incident confirms my opinion about Pentax. P-TTL is a mediocre flash exposure system. And if "mediocre" is a tad harsh, I'll say instead that my impression is that P-TTL is a weaker system than those used now in the best camera/flash combinations from Nikon and Canon. The Pentax 540 FGZ isn't as powerful as some of the flashes available for Canon and Nikon cameras. These aren't accidents; Pentax designed the flash this way. I just don't think it's a very good design.
But in addition, the hardware seems less sturdy than it should be. My first 540 FGZ developed a fatal problem - the zoom mechanism froze on me - after I had used the unit only half a dozen times. It had to go back to Pentax for repair at a time when I desperately needed it. And now this problem with the 540 getting stuck in the hot shoe.
I understand that many people use the 540 FGZ without problems. I myself have now used both of my 540 FGZ units without a failure for the last six months, in shoot after shoot.
But the problems I have had were not only real, they were serious - and they're hardly unprecedented. There are plenty of reports from other users whose zoom mechanisms have locked up, and the flash getting stuck in the hot shoe is something about which there are many threads in this forum. If the 540 were an inexpensive unit, sold to amateurs for occasional use, this failure rate would be acceptable. But this is Pentax's best unit and it's not cheap. My flash unit is as important to me as my camera. But the 540 isn't in the same league as the K10D/K20D when it comes to durability.
Bottom line
My next flash unit will be a Metz.