10mm Armstrong reversible ratcheting wrenches show up on Ebay from time to time, you should be able to find a replacement. I love mine have several sets in SAE and Metric.
I should say there used to be good deals on E-bay, not sure anymore since inflation. Prices on some UAS made tools have went up drastically. Several years ago I was able to get a brand new (open box) Armstrong 3/4 drive torque wrench (64-095) 100 to 600 pound for $200. Deals are out there but...