a camera lens of mine had SEVERE fungus. It typically appears as fine white lines starting at the edge of the lens, and trying to find their way to the centre. On the lens I had the fungus had reached the centre, phoned out for pizza, and was having a party with a bunch of friends.
In the case of this lens the optical symptons were that light was being scattered, so contrast was reduced - anything dark against the skyline (like a building, or a person) ended up a couple zones lighter than it should be. A couple of otherwise good shots had to be saved by burning in.
Your lens is probably no where near as bad as mine, and you're working in a more controlled situatuion, so you're probably just having to print with a bit more contrast to make up for it.
If it is fungus, getting it proffesionally cleaned is relativly cheap IF you can find the right person to do it. I live literally round the corner from a repair shop - I've taken a few things in, and each time I've walked straight out again: everything seems to cost 70 pounds ($120!) before he'll look at it (which may be reasonable for skilled time, but makes repairing most things not cost effective).
Fortunatly I bought a few things of ebay from a local camera dealer (he puts about 1000 things on ebay a week), and he passed it on to they guy he uses (which is no where near here!). I got it sorted for 20 pounds, which I think is great value. On the downside, I did have had a few glitches, and some stuff I've sent has had to go back for a second repair, but they were sorted under warranty without any problems. I know it's not much use to you in New Zealand, but if any UK'ers want details then PM me.