There probably is enough fungus to have an effect on your pictures. Flare, loss of contrast, soft image.
The lens is till going for over $300.

The group you want to get at is held in by the inner spanner nut/ring. it's visible in the picture and is the smaller ring with two notches at 180 degrees.
A cheap pair of pliers with the tips ground t fit the notches will work. If they fit correctly they won't mark anything. Slip and all bets are off.
You may need a small suction cup to get the glass out. Clean it with ammonia and wipe the barrel out with it too.
The fungus will just get worse if you leave it there.