fuel sender renew/replace?

[nicksimc at plu.edu]

A while ago the fuel gauge in my 82 4k started indicating slightly less
than full when the tank was full.  When the indicated level reached 1/4,
it would just drop to 'empty.'  It has gotten progressively worse and now
indicates 3/4 when full and drops to 'empty' after reaching a little under
half.

I've looked in the Haynes manual and in the archives, and
removal/refitting seems to be fairly simple but I have no clue how
repairable these are or how to identify a working one should I need to hit
the scrapyard.

TIA

Matt
82 4ks