I'd recommend going the battery change route first, it's pretty cheap to do it and realtively straight forward. Be sure to write down your tach time before doing this procedure, once you pull out the chip, all your customized parameters will have to be reprogrammed, tach time being one of them. you are right that the DPUs are no longer made, but it's not too hard to find a good used one, eBay and Barnstormer's have been good sources for spare parts for me. I've accumulated a decent stock of VMS parts (unfortunately no spare VM1000 DPU, but do have a EPI800 DPU) this way.