The main hatch frame was tried out before its final assembly in order to determine the right placing for stoppers to be placed on the aluminium. These would prevent the sliding canopy from flying off either end. The stoppers themselves were made from blocks of aluminium that came off some old window frame. These blocks were bolted to the ends of the aluminium glide strips on both sides, front and back.
The bottom sets of roller bearing assemblies at both ends would then come to rest against these blocks. Two small springs were added to the posterior blocks to buffer the impact.
The range of movement of the hatch forwards is much smaller because of the presence of the front window and so springs were not deemed necessary anteriorly.