I have seen these on eBay quite often.  That's where I got the one for my 8/e.  :-)
Also, it is possible to rotate the cam that engages the microswitches behind the key so
that the machine is "always on" and you can control the power with a powerstrip.
That's how my 8/e was when I got it.  It doesn't damage the machine but allows you
to power it until you can find a key.  -- Ian
  -----Original Message-----
 From: cctalk-bounces at 
classiccmp.org [mailto:cctalk-
 bounces at 
classiccmp.org] On Behalf Of SPC
 Sent: Wednesday, July 14, 2010 2:19 PM
 To: General Discussion: On-Topic Posts Only
 Subject: ACE xx2247 key
 Hello. I sent this request initially to PDP8-Lovers list, but I send
 the
 same request here in the confidence of some help.
 I am cleaning one PDP8E box with some boards inside. Previously to do
 some
 cleaning of the internal boards, I tried to fire up the computer
 yesterday.
 In appeareance nothing is wrong no strange smells, no burns, no clouds,
 no
 boom!, etc...)
 But... I don't have the front key :-)
 One ACE xx2247 is needed. I don't have one available, and is impossible
 for
 me to get one in my country (Spain).
 I would be grateful is someone could provide me one, or even a couple.
 Contact me off list if you want to discuss details.
 Regards
 Sergio