I hope nobody gets up in arms!
Soft solder a strong wire (ball the end of the wire to give it
extra holding power)to the area of the dent and gently pull on
the wire to ease the dent out just enough to disassemble the pen.
Use just enough solder to do the job so the you will have very
little to take off by hand and then remove the rest with
hydrochloric acid. Using the soft solder may be a bind but the
heat required should not damage any thing inside the pen.
I have done this with silverware in places that I could not get
into the back of.
Hope this may help solve your problem.
Major Boyce @pyramid
The greatest pleasure in life is doing what people say you cannot do.
EVERYBODY has a talent. What is rare is the courage to follow that talent to
the dark place where it leads.