What else can I check on a tumble drier…I’m at my wits end with the bugger!

I’ve got a Hoover H-Dry-300 heat pump tumble drier. One of those where the water collects in the door.

It’s not drying and I’ve no idea why. I’ve checked everything I can get at.

\-I’ve emptied the water (obviously but worth mentioning).

\-I’ve cleaned the lint trap filter in the door.

\-I’ve taken out and cleaned the filter (edit: condenser not filter) that pulls out of the front at the bottom corner.

\-it’s heating up alright.

So what am I missing?