Broken Tube Guide Key

6SN7?

The filament pins of 6sn7 are 7 and 8, you can use a DMM ( digital multimeter ) to identify the filament pins by using ohm meter, other pins will show open circuit except pin 7 and pin 8 have resistance reading.

I've had the same thing happen to me, and yes indeed, it does make a difference how the tube is aligned.... 

Tubes only go in one way if you can't tell gently spin the tube in the socket until you feel them start to go in on their own.

👍 Have fun. And don't wiggle power tubes again!

@noromance it was a clean break so it's impossible to tell.  I was able to figure it out.  There is a marking on the side of the tube that matches the orientation of the guide key.  I was able to confirm this by looking at the other tubes I bought.  

Yes.

You should be able to see where it broke off and align it up with the expected position on the socket.