My Planet Bike 5 LED front blinky is acting up. It sometimes does not work (no response to the on-off switch) until I take it off the bar mount and rap it on my stem a few times. Usually when a blinky starts doing this I retire it but it occurs to me that something really simple and easy to fix might be causing the problem. So, do any of you have any ideas? Dry it out? Clean the battery contacts? Etc? TIA (This Is Africa)