Ok, the pictures suck (I really need to upgrade my cellphone). There's not enough contrast to show what I'm about to describe, but my '59 Bassman Reissue (a.k.a. Tweed) amp is developing some nasty fungi. When I play guitar at home I usually do it with computer effects and my studio monitors, so my trusty amp had been covered with its plastic cover for about a month. How do I clean it without damaging the tweed finish? How do I stop the fungi from growing back? I had actually cleaned it a month ago when it started developing but now it got much worse . Thanks for your help. P.S. I added a picture of a spider in my closet for an increased drama effect.