Tighten up the front band. remove the bolts holding it in. take a slide hammer and use it to pull the pump out. relatively simple. But remember to tighten up the band snug, then you will have to readjust it when you're done.
Go to this link and it will show you how the front band is applied to the drum.The adjustment is simple,tighted to the spec for your applacation and then back off the amount of turns requiered and retighten the locking nut.Read the article and you will see and know for sure,Mrmopartech