Assistance identifying spiral return

There is no 3/8" balance that can support a sash as heavy as 52 pounds. No matter how strong the spring is, at 3/8" diameter it would simply bend in half the minute it's installed. 52 pounds is just way to heavy. 

I have a feeling the information provided is not accurate. Can you please double check these details for me? Can you also show me pictures of the hardware you're working with now?

I'm not sure there are any photos that would get us any closer to a solution at this point. There is no 3/8" diameter balance that can support that weight. They simply aren't made. These cap out at 34 pounds with the absolute stronger spring available in this size. Can you confirm that these are 3/8" tubes and not 9/16"? If they are 3/8", then I have a feeling someone installed the wrong parts in your window. There just isn't anything that matches your specifications.

That's not really something I can answer. If your original balance tubes were 3/8", then you typically can't use a 9/16" balance to replace it. There's just not enough room in the track. However, if you think that there is, then I suppose it's worth a shot. It really depends on your window, which I don't have access to to measure. You'll have to measure the space available in your track to determine whether a 9/16" balance can fit. Just keep in mind that our tubes are metal and not flexible in any way.

If the original tips on your balances were black, and if you have space for a 9/16" tube in your window, then odds are your original balances were in fact 9/16" in diameter. All signs point to that being the case.