Brass filter press pump

[devils11217]

I know these can go bad? How do you tell if your pump is going bad besides it obviously not moving any liquid or syrup

[Potters3]

Mine went last year ( us a air pump now) it just slowly slows down and then will not move anything. Noticed the most when you first start it had trouble pulling a prime.

[wiam]

And they usually get louder.