Before replacing solenoids, are all battery connections clean and bright, including ground connections? That would be my first step in solving the problem. Also, taking voltage readings to be sure the batteries are giving their all.
The solenoids can be figured out if you have someone else trigger the solenoids while you listen and feel for which one is 'clunking' when activated. Again, voltage readings across the solenoid's terminals can help determine if it's connecting or not.