Drift punch tool

If you wish to just replace the large white gear, by removing the roll pin, you will need a "drift punch" tool.  I did not do that, although it would save a few dollars.  You would do best to support the shaft in a vise, then use a "drift punch" tool to pound out the lower pin.  You only have to remove one to slide the gear off.  

You can find a punch tool from these sources (hey any excuse to buy a new tool, right?)  Here is a picture of a stainless steel drift punch tool:


I know Amazon, steritool, mayhew tool, ace hardware all listed them.  Search for a steel "drift punch" tool, a set of 1/8", 3/16", etc. should do it.  I see brass ones for sale but I'm not sure those are strong enough.  These are some decent tool selection companies to try first:
ONLINE TOOL SUPPLIERS THAT SHOULD SELL "DRIFT PUNCH" TOOLS


Use your drift punch tool to remove the lower pin, see arrow below:



You do NOT have to remove the upper roll pin (see below):