the belts on my new(used) mazda protege are squealing...
how do i tell if they are too tight or too loose...?
..and what is the best way to change them?
do i loosen the Alt..or the puller closer to the front?
Appreciate all the help given...

 

What year protege?(for reference point) How old are the belts? What is the condition of the belt? If grooved, the grooves should be running complete the complete length of the belt. If belt surface is glazed , change the belt. If you have two belts, change both at same time. belt should have approximately a one inch deflection by finger pressure in the middle between pulleys.
When does belt squeal? When you turn on lights or defroster or A/C or rear window defroster or any combination of those items listed ? Another Question to answer is how old is the battery? Check and clean battery terminals just in case and because it's go maintenence to clean them (use a mix of baking soda and water)
come back with answers to questions and we can help