TF: Remove the missiles. Fold the back down, folding the blast shield up out of it, then fold the sides of the vehicle down. Raise the two black supports up from the front of the vehicle, fold the front panel forward, raise it up on the supports at the rear to form a raised platform and slot the front supports into the front of the base. Missile launchers can be plugged into any one of the four 5mm peg holes at the corner of the vehicle.
Groundshaker's base mode has an odd half finished look. The exposed base components are in red, contrasting with the blue of the tank, but that just makes it more obvious that there's a panel in one of the folded down sides and not in the other. It looks for all the world like a cost cutting measure. There's two connectors for Micromaster base ramps on Groundshaker: The first is at the front of the base at the foot of the platform - all well and good - but the second is only slightly off to one side - the side with filled panel and at an odd angle. He'd have worked better with two ports towards the rear of the vehicle immediately opposite each other forming a through road across the base mode. The raised platform at the front of the vehicle is nice as a landing pad, though it makes me wonder if it wouldn't be more appropriate if Groundshaker came with a Helicopter Micromaster to land on it.... and thus were the other battlestations and base meant to have brand new Micromasters like Countdown and Skystalker?
EDIT: after I posted this review to The Hub Forum I was reminded that there's a < a href=http://www.transformertoys.co.uk/content.php?/transformers-image/toysheets/g1/uksheet07/2.jpg/image.html>catalogue that features a prototype Groundshaker. Included are a second filled in side panel, a third ramp connector - an opposite to the existing side one, a missile mounted on the cannon rather than a gun *and* a Helipad platform cast in red plastic with a yellow inset centre that rotates via a wheel on the front of the platform. Examining the actual toy we find the hole for this wheel is present and that the helipad base is cast in such a way that it expects both sides to have filled in inserts. As a side note the toy is pictured with the original colours for it's Micromaster.
Overall: Decent vehicle mode but base mode is a disappointment,