How do I tighten the ball head on my tripod?

I’ve had one of these for… maybe two/three years now. It’s my first and only, so I’m not very familiar with the longevity of tripod heads (so this could be just old age and wear and tear) but the ball head came completely loose the other day. Even when I tighten the knob, the ball stays loose (I can’t get it to sit straight) and just comes off.

Anyone know a fix for this? Or, is it time for a new ball head? (or tripod..?)