Tonight on the way home from a car show, I got into the boost a little bit. The car backfired massively and the turbo started to sound like a siren. Not like the usual whistle, but more of a whhhooooooo. I got home, in the garage I opened the hood and reved the engine a bit. Heard a strange noise from the turbo, like a rattle. I removed the large hose between the turbo inlet and the MAF sensor. A little weird looking brass nut fell out. Looks like it goes on the end of the impeller. Grabbed pliars, impeller moved in and out and bck and forth. What happened? How did the nut fall off? Do I need a new turbo? Their are some fins on the wheel damaged. The car is an 87 GN, with 40k on it. If i do need a turbo, where should I get it?