How do you know if an inlet baffle or an outlet baffle is bad or going bad?

Cannot run dishwasher, empty tub an wash clothes at the same time without gurgling or backing up in the tub or toliet. Septic tank has been emptied. Out in the field, the ground is wet and usually stays wet so it appears the water is getting out. One party thought it was the vents that needed to be cleaned out and then another party thought it was a baffle or baffles may have gone bad and would cost around $100.00. The clearnng out of the vents was $80.00 each. I am totally at loss. I would apprieciate if someone would offer their opinion. Again I just had the tank emptied, no gurgling water is following now. Thank you, Rick