My 550 EX has taken a beating recently. The red plastic covering the AF beam emitter is cracked, though I have that fixed with some superglue, and the performance is unaffected. The more important problem is that the zoom head motor has jammed the flash in the position closest to the top (105mm i think?) and will not move. The 550 detects this and looks like it is working around it. I use it in a bounce configuration or off camera with an ST-E2 all the time anyway, so it isn't a huge hinderance...however I think it is very inefficient on the batteries. Nonetheless, is it worth sending in for repair, or should I just spring for another 550 on eBay? A 550 on eBay goes for around $225 or so. I thought briefly about the 580, but I don't see the need for it as my 10D body makes no use of the advantages the 580. So, should I repair or replace?