The jockey pulley on my hardtail is riding against the 2 largest cogs.
It appears that there is insufficient spring tension even with the
B-screw adjusted fully in. The chain length seems right and there is
little force on the derailleur from the cable (it is the very flexible
IRD metawire).

After reading a number of posts to this group, I tried some of the
suggestions including a longer screw. None seemed to help. Manually
rotating the derailleur indicates that there is more than ample range
of motion available; however, it appears that the spring is simply too
weak.

Is the spring replaceable and is there a spring available that has a
higher spring rate? Is it possible to remove the spring and re-install
it with an extra turn or two to increase the preload?

The derailleur is a Shimano LX special edition that was only avaible
in a black and gold finish. The cassette is an XT with a 34 tooth cog.

Thanks in advance for your help.