I'd loosen & clean connections before buying a new battery. Lots of connections only get cleaned when a new battery is installed thus masking the real problem. In most cases when jump starting the battery terminal is bypassed and the jumpers make contact with the battery leads to the starter and a quick start occurs, but the alternator still has to charge thru bad connections, which it won't do, making the battery look like the culprit. Particularly with small batteries the charger clamps onto both the lead & battery post also bypassing the bad connection making it appear that the battery will take a charge but won't hold a charge. i.e. charger brings charge up, gets disconnected, tractor starts discharging the battery, and because of bad connections the alternator won't recharge. MikeD74T