I would have to take issue with ptfarmer over a number of issues in his reply.When the hydraulic cover is inverted during removal using the MF tools the dashpot piston can fall out. The special tools consist of a framework to allow the cover to hinge on the hinged pin lugs at the rear of the centre housing and a pillar to use as leverage which becomes a stand for the cover when removed. This allows safe and easy working and access.
The easiest solution to prevent the plunger falling out is to place an elastic band around the plunger body and over the adjusting screw. The elastic band can be cut and removed once the cover has been refitted.
The dashpot piston wedge will NOT hold the plunger in place. It is not designed to do that. The purpose of the 270B is to prevent the dashpot piston (not plunger) moving during adjustments.
"4 very long bolts" may well prevent you removing the hydraulic cover. The cover has to move rearwards slightly before it can move upwards. If you look at the front of the hydraulic cylinder you will see it is profiled to fit up close to the front part of the cover face. The correct 7/16" unc studs should protrude no more than 1 1/2" above the upper face of the centre housing. A turned or ground taper is useful but they should also have a slot cut for a screwdriver to remove them. It is essential that the cover does not move when it is in its location. The gasket can become damaged it is moved.
The attached image shows a page from the MF adjustments book. The roller removal tool consists of a spring clip at the end of a small handle. This is essential to prevent the roller falling under the pump. You may be lucky to fish it out but if not it will mean removal of the cover again at least. It is difficult to open the legs of the pump lever so take the greatest of care.
DavidP, South Wales