If you have the older 3100 model with the twist off blade, after twist off, check your blade housing and motor shaft bearing area when you remove your blade thinking you need battery replacement. Mine (also a 3100 but looking somewhat different likely older) was so jammed with 7 yrs of beard trimmings that it slowed the blade so I thought it was a weak battery!
Took a full 10 min with a 100 psi air hose to tease it all out but now is like new!!
