Bleeding master cylinder

Right let me start from the beginning, I've recently noticed brake fluid running down the outside of my master cylinder body dripping onto the floor etc and after several attempts at straightening the lid and adjusting clip tension etc I am no further forward. The cylinder was new 2 years ago and was fine for most of that time so I wasn't convinced the lid has been the problem anyway. I recently overhauled the rear brakes and during the bleeding process with the lid off I noticed upon the first press of the pedal I get a pretty high geyser/fountain ejecting from the rear brake portion of the reservoir, nothing at all from the front section. It appears to be shooting out of the forward most hole in the base of the reservoir, leading me to think I've got a big bubble of air stuck in the front most section of the cylinder. Does anyone agree with this and if so any good suggestions on how to shift it as I've tried bleeding from the line fitting but struggling on my own to do it using a pry bar ( wrapped in cloth between firewall and pedal link) . The new cylinder did not have a bench bleed kit with it and I can't seem to find one in the uk so unless anyone has a clever trick I'll have to order one and wait a few weeks to get it! The amount of splash produced by this fountain is no surprise it finds its way out past the lid seal! It hit the hood first time I saw it!
May thanks for anyone's help on this.
'74 360 duster disk/drum by the way