How are you determining that the regulator failed? You didn't explain what the failure was so that leaves everyone to speculate.
I don't think even the brand name regulators are made in the US anymore.
You can learn how to make a manometer on the web.
This past fall, I made a U tube manometer to measure my gas pressure. Didn't take 20 minutes. My 2001 mdl 5thW was regulating perfectly at 11" WC, while my 2005 mdl TC was at 9" WC. It wouldn't adjust up to 11" so replaced it.
The new regulator would only maintain 10" with 1 stove eye lit, so took it back and got another which worked great, maintaining almost 11" WC with 3 eyes lit and the generator running. I've had no more issues.
So, it's unusual to have 2 go bad but it can happen.
Let us know what the outcome is.