Simpson maxidry 457?

Hi there, I have a Simpson maxidry 457 & I need to replace the plastic wheel that spins the vent fan. Looking at the back of the dryer there are two wheels that has a rubber belt that runs on them...it is the smaller top wheel that turns the vent fan...not the bigger bottom wheel that turns the dryer drum that needs replacing. Is this something I am able to do myself or do I need a techy?