<Snip>
Is the starter quirk 'normal' (Saint Muir's book seems
to indicate this) and do I therefore just need to keep a hammer
handy...or
do I replace the starter, or do something else?
<snip>

Not normal .... but not uncommon.

First thing to do is disconnect the battery and clean up the terminals
and the connectors.  While it's disconnected, clean up where the battery
ground meets the body as well as the connections at the starter  you
should also clean the ground strap connections from the trans to the
body.  (Clean means "Shiny metal clean).

The above may cure the problem, but if not, for the "Near" future ....
carry a length of broomstick.  You can insert it through the wheelwell
without having to lay on the ground.  Tap the solenoid with the end of
the stick while someone holds the key in the start position (making sure
you're in neutral first).  It sure beats the hammer method.

There are a couple of other possible fixes, short of changing the
starter, that sometimes do the trick.  One is to install a "Hot start
relay".  Check the archives and you'll find lots of info.  The other is
to remove the starter .... then the solenoid ... then clean and
re-grease the solenoid.  (Need I say .... reassemble in reverse order?)

Good luck,

Mike
'84 GL 7 pass
'85 GL Westy