Need Help Identifying Parts

Hey Charlie. I understand; these old spiral balances with plastic outer tubes can be tough to measure correctly. If the outer tube's diameter is greater than 3/8" however, that's the one to go by, and therefore I'm confident you need the 5/8" Series 600 Spiral Balances--the fact your balance has a Blue Tip is also indicative this is the Series you need, since only the Series 600 uses that color. 

Now, as far as the length goes, we advise rounding up with spiral balances that have a length ended in an X-1/2" increment. Therefore, you'd need our S600-24. Let me know if you have further questions. 

Hey Charlie. The plastic tube is the equivalent to the outer metal tube on our spiral balances, and it's the outer tube diameter that matters. So if that outer tube definitely has a greater diameter than 3/8", then you need the 5/8" Series 600, there's really no other option. Again, the fact your balance has a blue tip further corroborates that, since blue tips aren't used with Series 900 balances. Let me know if you have further questions. 

Unfortunately I don't have a phone line from which to talk to customers. However, identifying the pivot shoe shouldn't prove too difficult. You will need to remove it from the window, send a picture, and give us its width and thickness. Those exact dimensions should point us to what you need.