I know I'm late to the party on this thread, but I am on my 4th or 5th Stages. I just kept complaining and they kept sending me new ones until one worked consistently. Current firmware is important. I keep a piece of electrical tape over my cap so that it stays tight, but a prong has broken off, so I may be writing them again eventually. This last unit has worked for a year.
Comments
Try this for some more tips:
http://support.stagescycling.com/support/solutions/articles/1000124355-recommended-settings-garmin-edge-510-head-unit
Hope this helps.
I would also get some butyl tape to wrap the stages in as most of the failures are moisture related at the battery cap over time.