on the mis-firing one--I have a 283 with the same problem....it is old and I guess the tube is shot....I bought it new and popped the hell out of it for....15? years....20 years...anyways....it started getting erratic .... now it will fire like ONCE when it's cold...after that, it'll never fire again till I put it away for a long time....I thought it was the trigger but now I'm pretty sure that something happens to the flash tubes where they never work right after a while...I didn't think you could wear out a gas, but, apparently you can....