Changing sparkplugs

Hi! I just bought a BMW 2000 (1969). I want to replace the sparplugs but can't get them out of the engine. I did not have a problem changing the plugs in my other car (a Ford) , but with this car a have a lot of trouble. The plugs are situated beneath the engine-cover fairly deep inside. You can't use a conventional wrench to get them out. Removing the engine-cover is no solution to the problem. Is there anybody who had the same problem or does anybody know how I could get them out?
Thanks in advance!

Rampicatore

Update : because of the long inactivity , alot of dirt was formed which made it very difficult to screw the sparkplugs loose. So don't bother to reply on this item anymore.