You may be able to snake the drain and make it work,
Or you may need to pull the paneling and get to the problem, if it's piped wrong.
The washer should be run in 2" and the p-trap needs to be vented.
The standpipe coming off the p-trap needs to be at least 18" long.
If the existing pipe goes into a cast fitting, often times they are a 2" hub, in which case, you can bump the size up to 2".