Mould in this time frame is easy to figure out: put your head in and if it smells mouldy...then it's mouldy.

Functional is also easy to figure out: plug in, and turn on. If you have a machine that has a cycle...like the dry, then try using the cycle (wet down old towels that you don't care about and run them through a dry cycle).

If you have a few thousand dollars to spend on these three then get new one's if it makes you feel better. If you are on a bit of a budget, work with what you can...and buy what you feel needs purchasing.

My concern = mice and what they leave behind. Stoves/ovens are famous for smelling like mouse urine after being stored. Plenty of cozy places for them to jump in and hole up for a few years. They LOVE stoves/ovens. The urine would be more or a worry than mould/not functional.