If its a all metal hot end that jam could just be more resistance than your extruder can currently handle. PLA gets warm and sticky in the cold end but if you have a strong extruder and a tight tensioner you can power through this. Alternatively you can try to clean out your heatbreak/hotend and put a bit of olive oil in and bring it up to around 240 C for a few minutes, this should reduce the friction (i do this cooling fan off so the cold end heats as well)