Small Engines (Lawn Mowers, etc.): Primer Carb bulb, retainer ring, flat screwdriver

Question
John,
I need to replace the Primer Bulb on the Craftsman Rotary Lawn Mower.  It is a 7.0 hp, power propelled 21" rear discharge Model 917.378644.  I know the replacement part is part number 674395.  I have not bought the part (mine is ripped from the center hole both ways), the mower will not stay running.  I have put up with this until now.  How do I take the old part off?  There is no book explanation in the little manual they send with the mower.
Thanks,
Rich

Answer
 Hello Richard:

 The Bulb has a Retainer Ring at the Base of the Bulb. Use a Small Flat Screwdriver and Pop This Retainer Out. The New Bulb will Come with the New Bulb. You can View a Breakdown/IPL of the Engine at this Addy http://shop.briggsandstratton.com/BShopProductListingPage.asp?rsvp=0&PARENTID=0&... and Enter the Model Numbers 128602 and the Type Numbers 0259 and Click Search. Then Scroll to the 2nd Listing and Click View PDF. This will Download the Breakdown/IPl for the Engine. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks. Be Safe.

 Good Luck

 Respectfully

 John

 PS:  Happy Thanksgiving and Merry Christmas