How to get a musty smell from front loader?

Where is the front loader? Is it attached to another vehicle? What do you use it for?

If you mean washing machine, run an empty load after pouring white vinegar in the soap dispenser.

https://m.wikihow.com/Get-Rid-of-Mold-Smell-in-Front-Loader-Washing-Machine

Pull out your owners manual or look up on line on the manufacturers website.

My manual says run an empty load with cloryx bleach in the bleach dispenser. Always leave door open between wash loads.

Yes, the rubber seals and the spaces in between, on a front loading washing machine should be checked periodically for acccumulation of lint and hair, and then wiped down with a bleach dampened cloth.