utcmoc75

If it is the same as my 2005 Sportster there are three plastic "darts" that hold the seat base in place. If the seat base is moving, one or more are probably already broken. On my 2005 I pulled the seat base upwards until the remaining dart(s) pulled free. This could possibly damage the darts though (There may be a better way, but I don't know it). I just went ahead and replaced all three. Seems like they were $3 or $4 each. The heads of the darts rotate to attach themselves to the seat base. Then line up all three with the hull before pushing the seat base down.

New owner of a used Sportster 4TEC SCIC here. Thought I would show what happened to my purchase. Bought it when the weather was cold, only started the engine, didn't get to go for a test ride. First time out several months later, everything was fine for about an hour. While making a left turn at about 25-30 mph, there was a loud bang and the reverse gate was gone. The attached pictures show more of what happened. Reverse gate gone, support bracket broken in two pieces, both reverse cable ends bent, the shifter base where the reverse cable was held also broken. Fortunately the reverse cable still held the parts where it was attached but still required a laundry list of parts. During repair, it became apparent that there had been previous work done and must not have been done correctly, I suspect that the reverse gate was not locking securely in the forward position. Anyway, the final tally on parts was right at $1000 (a new shifter was half of the cost since you can't buy the base except as part of a complete assembly), without any labor. I was fortunate that I was able to have a friend that was familiar with these boats to do the repairs so I didn't have to pay for labor. Just thought folks might be interested.