My SD3 clogged today after running a mere three inches or so of black.  Someplace here were dissassembly instructions, guess I need to go find them.
Addendum.  I placed a shallow container under the extruder and allowed it to soak for an hour or so.  Then I made the adjustments suggested by solidoodle, tightened the tensioner, increased the extruder temp to 200, emitted a length of black filament, and proceeded to make some awesome prints!
I am happy again.

Glad we could help!

Just wanted to report that I had major clogging issues, approx 4 times in 1 lb of plastic, using filament purchased directly from SD. They seem to be aware of the issue, and the new plastic I just purchased from them seems to be working better. But I never had even 1 clog with 5 lbs of plastic on my TOM. The good news is, I am now an expert at cleaning clogs on my SD2

The bad news, there is definitely some crappy plastic in circulation. Hopefully SD will exchange it?

Here's the thing:

We use the black filament all day every day. All of the pieces of our printer are made out of this same black filament. We have had absolutely no issues with it in the shop. We have about 20 early model Solidoodle 2s chugging away on the stuff, and there has never been major clogging issues. It is somewhat odd in our minds that this would happen in the field, and not in our shop where it would wreak havoc on our assembly line.

So, while some people have been having trouble, it is very hard for us to say that there are major issues with the black filament. We use it for everything, and it hasn't been gumming up the works one bit. We don't want to deny the issues some people have had, but perhaps the problem extends beyond the filament to calibration / generalized clogging issues.

nah nothing elastic inside, sonds like your hitting off a piece of unmelted filament..

I'd be looking to dissasemble it myself , but i have a spare couple of nozzles exactly for this scenario, i can change straight away and then fix the blocked nozzle...this in itself can take a few days as  i generally soak the nozzle in acetone for a day or even two prior to cleaning it.

I also dissasemble the nozzle from the acrylic extruder/stepper motor, then  simply reconnect the nozzle assy with the  two wires to the wiring loom and and leave it suspending in air.. then i just heat the nozzle up from RH...once it gets to about 100 degrees, i gently pull on the filament to pull it from the barrel... you dont need to pull too hard, but it needs to be done before the plastic melts... you end up pulling out a single complete soft piece of ABS the dia. of the barrel..if your timing is good, it should by in large come out in one piece, leaving only the nozzle to be soaked overnight.

works for me so far!

The spring back you're getting is from the compression if the plastic inside the barrel. If it's not coming out the nozzle then the nozzle is clogged.

Try pushing a guitar string through the nozzle up into the barrel to try to clear the blockage. As far as I'm aware there are no red bits in the hot end. But anything appearing here doesn't seem like a good thing, (unless it's locktite red? -but as far as I know this isn't used).

I was trying to use PLA but the prints weren't as good. Also, I'm running at .2MM, half way between .1 and .3MM. I'm real happy with this as I feel it gives me a bit of both, fine layers with good feed. I still need to work on the 'cobwebs' as I call them. These are the fine threads between print towers when the part being printed isn't a single column item.

I am so fed up with this and become vexed by only looking at all that potential and beautiful machinery going to waste. Not to mention the money I paid for it. I'm very dissatisfied with this. "Spend 5 hours cleaning for 5 minutes shoddy printing." This wasn't what they advertised.

Makerbot printers have always had a rigid plunger rather than a spring, so it's up to the user to figure out the right tension, and if the the right tension changes, the plunger can't change to accomodate it.  That's always been a problem with their extruder, and tightening the Solidoodle's idler arm enough to keep the spring fully compressed all of the time removes the benefit of having the spring in the first place.

*First, tighten the swing arm --  The idler/swing arm that I made can really make easy work of printing with black.  I could never get it to print good before with the filament, but now that I have revisited it with my idler (which I can tension even more) all I can say is "GG" clogs (it pushes everything right through and I don't get dust since the grip is so tight.)  I 100% agree with the needed temps being higher for black.  I run it at 200 and everything else is 192.

I used to use this approach, tightening the idler spring right down until it was totally compressed, and then backing off a turn or so.  I now keep the idler spring set so that almost none of the screw shows (i.e., much looser).  This seems to have fixed some problems I was having where the extruder would fail erratically (digging divots in the filament).  I was also seeing a lot of filament shavings, and now I am seeing none.  My point is that having the idler very tight may not be universally good.