Do I have to take aprt any part of the attachment to get the belt on.

Model #?; I can lookup a generic belt number probably.

Yep, most likely. I just changed a sears belt twice.

My snowblower has belt motion and a chain for the auger. The engine is in the middle of this.

The engine bolts (slots in frame) tensions the chain for the auger and there is a separate tension mechanism for the belt. For bolts have to be loosened. Tensioned with something like a crowbar and tightened.

I had to loosen the engine bolts and the belt tensioning bolts. Remove the chain and then the belt.

Yours may be different. Need the model #. Diagram should be at www.searspartsdirect.com

Model number is 917.253725 just need to know if I have to take apart some of the frame to get the belt on

It is a 40 inch snow thrower attachment from Sears really old I have the manuals but it doesn't say how to do it.

Sorry model # is 842-260621

Diagram is here: http://www.searspartsdirect.com/partsdirect/getSubComp.pd?modelNumber=842260621&productCategoryId=1500650&brandId=0247&brandDescription=CRAFTSMAN&modelName=40%22-SNOW-THROWER-ATTACHMENT&diagramPageId=00002&componentDescription=MAIN%20FRAME&documentId=00014439&blt=06

This diagram doesn't show me how to change the belts

Can you take a picture of the area.

Probably item #25 loosens on a slot with 4 bolts. Take a look.

How easy is it to access this area?

Hi,
Perhaps this would be of some assistance.
advice on mounting snowblower - MyTractorForum.com - The Friendliest Tractor Forum & Discussion Board and Best Place for Tractor Information on the web!!! (http://www.mytractorforum.com/showthread.php?p=1021237)
Peace,
Clarke