Flash Timing Off?

[sandmansf]

I have a Rebel XT camera and a Promaster 7500 flash attachment. Everything was working great until I stopped using it for a while and left the batteries in the flash. One of the batteries leaked and corroded one of the contacts on the piece you use to cover the battery compartment closed. After I cleaned the contacts and replaced the batteries, the flash was turning on and off sporadically. Someone told me to use some vinegar on a q-tip to clean the contacts better. I did that and the flash seems to be working well now. It's not turning off on its own anymore.

However, now when I take a picture using the flash indoors, it doesn't look like the flash is firing at all. The pictures are dark. The flash is definitely firing since I watched it and was half-blind for a little bit.

I figure the timing must be off now. Perhaps I changed something without realizing it? If I take pictures using the XT's built-in flash, the pictures come out fine and notably well-lit by the flash. Is there any way to adjust this on the external flash or am I hosed and need to buy a new flash?

Any advice would be greatly appreciated. Thanks

[sandmansf]

Ok I visited a local camera shop and we figured out the problem. I thought I would post the resolution here in case anyone encounters the problem in the future.

I had purchased this ProMaster 7500DX flash back when I had the Canon EOS Digital Rebel. Everything worked great. Then I sold the camera and bought the Canon EOS Digital Rebel XT. I could have sworn that I tried the flash with the camera but I guess I hadn't.

At the store the clerk tried a new flash with the same result. He was saying that even my flash worked fine until I told him to take a picture in the dark. He tried the Canon brand flash attachment and that worked fine. He was about to give up until I told him that I originally used this flash with the older Canon Rebel. Once I told him that he apologized since he knew that Canon had made a change. He got out a more recently manufactured 7500DX flash which ProMaster adjusted to work with the newer Canon XT camera. It worked great! He offered to take back my 2 year old flash and give me the newer flash for $50. Considering I hadn't bought the older flash from him in the first place, i jumped at the opportunity.

BTW, he assured me that this flash will work with the Rebel XTi as well in case I decide to upgrade again