I've found a suitable replacement edge connector for the Sega SC-3000 if anyone ever needs to replace one due to bent / broken pins.
EEA22DTBN (PBT / Tin plated contacts, 22 pins, dual sided, 0.180" tail
length, no mounting ears, 0.610" body height, 0.370" body depth, 0.150"
row spacing, right angle mounting).
I put a bit of super glue underneath the edge connector before soldering it in to help take some of the strain when inserting / removing carts. The original connector had some sort of adhesive there too which I had to lever up with a screwdriver when removing the original connector.
Note - I've only done mechanical fit tests and basic continuity tests to the pins at the back of the cart as this SC-3000 mainboard is dead. The fit is a bit tight on the carts, but I assume that will loosen up with use.
The EEA22DTAN could be a slightly better alternative. That only has 0.100" tails instead of 0.180" tails, as the 0.180" pins poke a fair way through the mainboard.
Note also that the row spacing on the SC-3000 is 0.125", not 0.150". But the pins bend into place so easily you might not even notice the bend if you didn't know the spacing was out.
The insertion depth of the cart PCBs into the slots is a little shallower than I would like, but it still seems to get an acceptable grab on the cart contacts, although only about the last 1-2mm or so.
I'd just like to say a huge thank you to Lucinda over at Sullins Connector Solutions who helped me narrow down the choice of connector.
You can see photos over at http://www.smspower.org/forums/viewtopic.php?t=14114