Very spotty render. Fireflies? I'm creating a model, and getting a lot of fireflies. I've read that these can be caused by poor lighting and by low render samples, and can be reduced by clamping.

However, I've got 2 lamps going, and I don't want to keep adding lamps until I have no shadows. I'm using 500 samples. I tried 1000, didn't help. (Using cycles render). I've tried all combinations of setting direct and indirect clamping to 1. The last helps some, but not enough to justify the reduced picture quality.


 Note the inside of the drive ring and the back of the radio antenna.

Edited to Add:

Thanks to Todd's suggestion below, I redid the render using Branched Path Tracing, and the result was much better. Only thing I changed was upping the samples to 250.
The best way to trouble shoot a noisy image, is to render all the main colour render passes (Dif, Gloss, Trans, Sub, Emission and AO) out, and inspect each one. You'll see one or two that are really noisy, and then you should be able to adjust your samples to clear them up. 



I'm a big fan of Branch Path Tracing mode, because it lets you reduce samples in passes that don't need it and increase samples in those that do. I'm fairly certain you should be able to get something looking decent for 500 samples, but you may have to redistribute them differently.