Yeah, soap and water is fine. Take out the valves and everything will be fine. Just make sure after cleaning that you rinse thoroughly with water to make sure all of the soap is gone.
I applaud you for cleaning your instrument, because there is probably a real good science project growing in there. I cleaned my entire fleet of instruments, and saw some pretty nasty stuff.
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There's a solution that most music stores sell that you can use as well. That and a tub of warm water should get it.
And as number1 said, rinse thoroughly.
Nothin worse than using a snake and pulling out a cluster/clump/chunk of something alive.
Alternatively you'll see an improvement in your sound lol