[Exim] Spool file is locked. How do I unlock it?

I was trying to debug / watch some of the mailer processes using strace on sun
solaris.

I've had this happen with other processes; when you Ctrl-C out of strace, the
process sometimes gets irritated and hangs or dies.

Well the process died in this case, and Exim thinks that the message is being
handled by another process. But that process has died. Whenever I try to
force the message etc. I get "Spool file locked, handled by another process,
yada yada yada"

So how do I get this message back into the run?

Delete a lock somewhere?
Get exim to prove to itself that there is no process serving that message?

Thanks much!

--Brett