intermittent problem Sigma EF-500 DG Super

I bought this flash used and it has worked well in light use for several years. However, lately I have experienced some intermittent problems.

Sometimes, the flash apparently fires (according to my wife, anyway) but it barely puts out any light. The EXIF info says that it fired.

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Electrical connectivity issue, most likely.

Clean the contacts on the flash and hotshoe with a pencil eraser and see if it helps.

Did cleaning the contacts solve this issue? I have the EXACT same problem! I've had the ef-500 for about 2 years now, and the 40D is only about 6 months old. Over the past few days it's been terrible. About 1 in 3 shots is under exposed even though the flash fired. If I adjust the flash head, then it's good for a while, leading me to think that it's got a loose connection in there somewhere.

I'll try the eraser trick...

The contacts did not look dirty to me, but I used an eraser on them anyway.

so far, cross fingers, knock wood, it seems to work.

It does not have the greatest build quality.

rdsmith3 wrote in post #6970436
The contacts did not look dirty to me, but I used an eraser on them anyway.

so far, cross fingers, knock wood, it seems to work.

It does not have the greatest build quality.

Great... I think, in my case, the flash is toast. I cleaned them like 5 times. Then tried the flash on two other cameras, all with the same results. about 1/2 the pictures the exposure is messed. To much or to little. and the flash is firing.