Question edited for clarity.
Question moved from Cars and Trucks category.
Yes the contactors take all the strain. The internal contacts are probably damaged, just replace it as they do wear out.
Soak the shaft and impeller splices with diesel fuel or store bought nut/bolt loosening spray and tap often over 24 hour period while it soaks and permeates the contact area. Tap impeller with a wooden mallet to remove,
The 24v is called the secondary and sometimes called the out-put. Make sure you have 240v on the primary, sometimes referred to as the in-put. If you have primary voltage then you should have secondary voltage, if not then replace transformer. Make sure the secondary, 24v control fuse is the correct size and present. If the secondary is shorting together or to ground somewhere, it will cause damage to the transformer.
Call a qualified electrician. More information would be needed to accurately trouble shoot your issue. Do you have automation connected to your heater? Is the heater trying to fire when the pump is off or is it ONLY the fan?
Try disconnecting your Water Pressure switch on the heater and see if the issue stops. With WP switch disconnected the heater should not work and the fan should stay off. Replace WP switch and see what happens.
Call a QUALIFIED electrician.
the prologic control unit will not offer programming for what you seek. the most detailed timers will offer weekday or weekend for each pump speed. you may want to get a remote system so you can control functions from your smartphone