I would call them and ask. I'm pretty sure at work we mail all our Proto warranty stuff to Motion Industries.
From their site.
The Proto Industrial Customer Service Center is located in Conyers, Georgia and is available to support any and all of your service needs. Our customer service team can assist you in everything from locating a salesman or distributor, to providing warranty information or product repairs and torque wrench/torque multiplier certifications. With over 100 years of experience, the Proto Industrial Customer Service Team can help you with all your Proto®, Blackhawk® by Proto, Expert and Stanley® tool needs.
Office hours are Monday - Friday from 7:30 am to 5:30pm EST.
For information related to Proto Air Tools, please visit servicenet.protoindustrial.com
Proto Industrial Customer Service
2195 East View Parkway Suite #103
Conyers, GA 30013
USA
Proto Customer Support
Phone: 1-800-800-TOOL (8665)
Fax: 770-648-9108