John,
I have replaced many GC sight pins.
I use a 'gauge pin' made of hardened tool steel, cut to length.
These pins are available in .001" increments from any of the industrial tool suppliers,
such as MSC, for $3 each or so.
I'd suggest using a pin .001" over the hole size, so as to produce a press fit.
I usually use a drop of red loctite on each end as further insurance.
Chuck
I have replaced many GC sight pins.
I use a 'gauge pin' made of hardened tool steel, cut to length.
These pins are available in .001" increments from any of the industrial tool suppliers,
such as MSC, for $3 each or so.
I'd suggest using a pin .001" over the hole size, so as to produce a press fit.
I usually use a drop of red loctite on each end as further insurance.
Chuck