I suggest you move this question to the tractor forum and be specific in the details. Does it run until you disengage the brake? Upon engaging the deck?

This is just my opinion but I think your mower will last you quite along yet cuz you are not abusing it and you seem to be maintaining it very well.Who can really say how long any machine will actually last before things go wrong?I think that the better you take care of your JD the more hrs you are going to get without issues. Good Luck To You!

I have a 1993 john deere 425 that starts hard. there seems to be no spark the first few times you try and then all the sudden there is. when it starts it runs ok on low throttle but when you push the throttle up the governor kicks in. Sometimes it straightens out and runs great and sometimes it dose not.

After you discovered your mistake, did you then hook up the charger the correct way and resume charging the battery? You must understand that batteries are actually capable of being "charged backwards" and when you hooked up the charger "in reverse", you were actually "de-charging" the battery (provided that your battery charger is "tough enough" to withstand that kind of abuse. Some are.) So, if you did not hook the charger up correctly and resume charging, the battery would have had less power than before you hooked the charger up in the first place. You can try hooking the charger back up (correctly of course) and charge the battery up. Beware that you might have done some damage to the battery, battery charger, and/or some components of the engine charging system. You can rarely do a charge or a boost start using reverse polarity without suffering some (or a lot of) damage). Good luck.