86 Coolant gauge problem

[Suffolk GameServer LAN]

I saw one of the cars stilling around here had the black backing of the
gauges had pushed out to rub against the needle.
Similar?
-Scott in BOSTON

car is a '86 5kT.
coolant gauge needle doesnt register anything till about 10 min after
driving
car....kinda like its "stuck" and then finally registers and starts moving
up
when the rad fan kicks on.. its intermittant.   any ideas as to whats
causing
the coolant gauge needle to "stick" and not register right away?
thanks
chris
'86 5kT