Candy washer dryer - Drying problems

We have a candy washer dryer (model number supplied in attached pics) which is around 3 years old now, in the previous house we used it as both a washer and dryer with no issues, we have since moved house which has a integrated washer so we have just been using our candy as a dryer only keeping it in a cupboard under the stairs, the first few month we lived here it was working fine (last winter). We haven’t used it all summer but now we are starting to use it again with the weather changing. So normally we put a load in to be dried and it senses how long it takes and begins the program which is always around the 2 hour mark, recently it does just this but after around 10 mins into the cycle it jumps to 4 hours remaining, the program has never taken this long even when we put small loads in the time still jumps to 4 hours. I always leave cupboard door open when on, I have checked and cleaned filter, the fan is running and it’s getting good airflow and draining water ok (it isn’t plumbed into water as we are just using it as a dryer but the waste is in a basin to drain), it’s doing all the right things like rotating, getting warm and draining water just the time it is taking has doubled.

Thank you all in advance for any help you may have.