Mine on a PB just about falls out on its own once the front bolts which locate the springs are removed..... A judicious blow with a mallet from the inside outwards will loosen things up . The tube has cut outs to locate it into the dumb irons and age, rust, paint and time often makes it a bit sticky.
Its absence does make the chassis a bit wobbly in front of the engine mounts and think about how the chassis will be supported before doing it. Man sitting on branch with saw in hand comes to mind.
Hi Robin Did the job this morning. Removed the dampers, and spring eye bolts with axle on jack then lowered the spring eyes sufficiently to clear the knuckles. Scissor jack inserted crossways between dumb irons did the rest......worked a treat. Thanks again for your help. Very much appreciated. Regards David