I have a Tri-Tronics Flyway Special XLS that has recently started giving me inconsistent stimulation on all levels. For example, if it is set on level 2 and I hold down the continuous button, it might initial start out at 2 but then have a sudden surge up to 4 then go back to 2. Same thing with the nicks, it might be right sometimes, but other times it different. Has anyone ever had this problem and if so what was the problem with it??? I was thinking about changing the batteries, as they haven't been hold a charge very long and thought that might be the problem. Any suggestions would be appreciated, I started to collar condition my pup and had to stop because of it. Thanks.