So I recently acquired a NOS Toolzall Pro, complete with sheath, box, and manual... And it has serious side-to-side play in the pliers. Just wondering if this is a common issue with the tool, and trying to decide if I should send it back to the seller to exchange for one that maybe isn't jacked up. The listing has several yet in stock.

I would send it back and ask for one with no issues.

Bear & Son have been known to let seconds out of the factory, and they get sold as regular quality tools, so you may have received a faulty one (or it might just be slack QC). 

It would be worth discussing with the seller about the quality of any potential replacements before deciding on a refund vs replacement.

Update for anyone who might be interested;

I contacted the seller in an attempt to arrange an exchange, but never received a reply. In the end I just decided to initiate a return and get a refund. Somewhat disappointed as the tool seems pretty cool and I was keen to try it out.

Not that I needed a new tool, but you know how that goes 

That's disappointing and poor service on the sellers part 

Update for anyone who might be interested;

Thanks, I always like to hear how things turned out

I contacted the seller in an attempt to arrange an exchange, but never received a reply. In the end I just decided to initiate a return and get a refund. Somewhat disappointed as the tool seems pretty cool and I was keen to try it out.

You can only speculate that they knew the MT was faulty before they sold it (or maybe they are just bone idle) 

Not that I needed a new tool, but you know how that goes 

There's always that reason excuse