Reversing the Hf leads?

[gearfreak]

Can be worth checking the HF phragms to see if they were hooked up 'correctly' / as you expect them to be.
Carefull though!

If markings are not clear, the battery test (1.5v or less w/resistance imo, not 9v) can be used to double check.

IME you cannot go by the ancilary molded lettering (e.g. 'altec lansing') on the phragm clamp ring.