Yeah, the main pump is much easier to change than the prepump. The fittings on them are sometimes pretty rusty from being exposed to the elements. Use new hose clamps if necessary. Also change the filter when you change the pump ( same location) and use only Bosch pumps. Are you replacing the little rubber line on the pickup tube while you have the intank pump out? It's a good idea to do so since they crack and draw air into the system.

Good luck,
Dave