Bosch making loud rattle noise and not working

Hi and thanks for any help.

Do not use this dishwasher very often but tried to run and now has an odd rattle noise coming from underneath the unit on left side. Almost sounds like something rattling around in an impeller area. Will not start the cycle or I should say I don;t think so as I have not let it run very long as i don;t want more damage if that is possible.

I assume this is a bad circulation pump but would like to confirm before i start part chasing ;> Also have never replaced such a part so need some guidance as to the skill level required.

Thanks

Rich

Was wondering if I could get any help on this topic Thanks

Rich