Dishwasher, kitchenaide

Model Number: KDTM354DSS3
Brand: KitchenAid
Age: 1-5 years

I need to replace the main pump&motor any suggestions on where I can obtain service manual diagrams help tips etc.

I assume you have googled for the documents?

I am not sure if the following is an exact match to your unit but it should be close.
Hopefully it will be of use to you.

https://www.youtube.com/watch?v=HJhjGFijie0