Difficulty level should be revised to Easy but perhaps Moderate makes sense depending on how swollen the battery is.

Wasn't even aware that my battery was about to die until my trackpad started to stick and eventually became useless.

In my case, my Early 2011 (MacBook Pro 8,2) battery had over 1,300 cycles and the swollen battery was pressing against the trackpad rendering it basically useless.

Purchased a 3rd party battery off OWC for $99, arrived 3 days later and magic. My cycle count is zero now and the trackback works perfectly.