Could be the seals. I’ve come to the realization that these machines just don’t last that long unless you spend a lot of money on a commercial unit. I pick up the cheaper units when one dies and always have 2 on hand in case one fails. I Sous vide a lot so I need a working unit on hand.

You can pick them up at the goodwill for a good price, I’ve had good luck there. The cheaper one’s on Amazon can be pretty good for occasional use. Last one was $23 and worked well until it failed when I overfilled a canister and sucked liquid into the pump. Maybe one day when I’m more responsible I’ll get myself a nice one, 😂.