I'd suggest make sure you don't have any binding in the fork,
lubricate the seals and bushings with a silicon grease, or silicon spray.
the internals of the fork (the spring/elastomer part) use a non lithium
grease to do this. (lithium grease will eat the elastomers and seals away)
In regards to making them softer, sometimes the coil section of the fork has a small rubber bumper/elastomer in it, removing this bumper can offer you a bit more sag and a softer overall ride, although this may come at the cost of
the vague damping effect given by the elastomer. Meaning the fork might feel more springy and less controlled.
Ultimatly the forks are not worth spending any concernable amount of money on. (more than $10 and it's a waste) so just try to make them work best you can without spending money. They are incredibly simple forks to work on, so you should be able to work out whats what with a few spanners and a spare 20 minutes.
Carefully examine your forks to make sure they are not bent.
Worst comes to worst, every now and then a nice set of older forks comes up for sale on here, if you shop carefully you can pickup something with incredible performance for less than $300. .just be wary of worn out forks.
Most higher end marzocchi oil bath forks that are no older than 2004 should still be in good nick. There was some issues with the 2001/2002 forks so steer clear of those. 2003 was better, but 2004 onwards would be your best bet.
most of the other brands of forks, there designs didn't lend to the fork being in good condition after 4-5 years, so be on the lookout for rarely used forks in other brands. well used forks are worth steering clear of.
regards
Juls