I'd try the following steps:
1) try to identify which main gear leg is causing this. Sometimes it's just the center body gears, sometimes it's all of the main gear set.
2) This will be tricky: I'd try to remove the gears, sand them down a little bit and glue them back.
This might work, but do it at your own risk!
Another option is try to remove the nose gear and make it "longer" by inserting some filling at the gear hole and gluing the nose gear back.
A small ball of modeling clay might do the job.