24 psi seems to be low for this pump. Do you have any idea what resticion was built in the system (3/16" I.D. line at the tower)? Do you have access at the tower to change this?
If you have the right pressure at the pump and correct balance in the system run, the major issue you will be confronted with is if the beer you are delivering to the pumps is not degassing or over carbonated. Another condition to be aware of is if the cooling system (glycol system)is maintaining the correct beer temperature between your cellar and the towers.
Are you dispensing directly from your vessels?
Scott Zuhse, Instructor
Micro Matic Dispense Institute