As you mentioned, this is most likely a pump issue. Sounds like your pump is starting to wear out. There is a howto on changing a returnless pump without dropping the tank here:

http://www.contour.org/mods/mods.php?s=howto&displayid=39

Beer is my Gatorade. Hooray Beer. '98 "Sport" Pacific Green '98 E0 SVT Silver Frost Pictures