Strange cause mine was on a honda VFR for 6 years then fitted to same one to my honda RR8 when I changes my bike it is as good as new!
Fitted one to my car and one to my XTR so I can use the charger on all once a month.
On the XT, I have fitted it under the seat as opposed to sticking out (on the other bike) so I remove the seat to connect to it.
What can happen I notice is that the rubber body can slide down the cable so that the cap never fully close on the top & around it in which can you can get the probs you describe over time. Worth checking