Drive shaft passes through a bushing and can be a bear to remove if all coated with carbon and crud.   Assuming there is no other problem, the good news is you don’t have to remove the drive shaft. The pump can be removed by simply prying/rocking it out.  It likely has some corrosion around it.  When you reassemble it, notice the pump housing, plate and flat spring are all keyed for proper alignment.  Clean up the parts so they slip together easily and pay attention to the keys.