This may seem obvious to some but after soldering a few wires upside down on the underside of my playfield I thought there must be an easier way.
Since I had a problem with my solonoid driver board which locked all my coils on in my Stern Galaxy I decided it would be a real task to check and change each coil diodes while working upside down in the dark interior of my machine.
I already had the solonoid driver board out and I reasoned I only had to unplug a few more connectors and I could simply remove the whole playfield to a better location.
I marked where each connector should go, may not of been neccesary as they are keyed so you can't mix them up for the most part but better to be safe.
When everything was disconnected I simply lifted the whole playfield out and took it outside where I placed it on a aluminium scaffold. Be sure to support the underside of the playfield if you do this as you don't want the whole weight of the playfield resting on fragile plastics. I found a handy piece of pine and placed it underneath where it picked up a couple of playfield stand-off screws.
I don't know if this solution will apply to all machines, depends how easy it is to undo the loom plugs and if the playfield is secured somehow. (mine was just resting on a couple of wooden runners.)
Here is a pic of the playfield undergoing repairs.