Can anyone help me repair/troubleshoot a studio condenser mic?

I snagged a free Marshall MXL 2003 studio condenser mic.  I tested it before I left for vacation (through the sound system at the theater) and it seemed great.  I basically tested to see if it functioned.  My voice came through the speakers so I didn't go much further into things like listening for anomalies.  Now that I'm up here in the wilderness trying to record some nature/ambient sounds I'm noticing it sounds like a really dusty/scratchy LP record.  I'm putting it through a Scarlett 2i2 USB interface to Audacity.  Tried two different XLRs and plugged in a Sennheiser e835 cardiod and it was perfect.  The only common noise-making entity is the MXL mic.

Just wondered it this was a common thing like, "when a condenser mic does that it means [insert easy fix here]"

In reply to Curtis :

Are you running phantom power from your interface, or does the mic use a battery?

The interface has phantom.  Mic doesn't use batteries.

MXL with phantom = noise
MXL without phantom = no noise
Sennheiser 835 with phantom = no noise
Sennheiser 835 without phantom = no noise
XLR only (with or without phantom) = no noise
Laptop plugged in or not = no difference
window fan on or off = no difference

After a bunch of tests, the noise seems to be obviously coming from the mic itself.

I pulled the barrel off and looked for obvious cold solders and loose things but found nothing.  Seems like the element might be failing but I'm clueless on these things and wondered if there was an obvious thing that was an easy fix.