I replaced the original bolts with M10 high-tensile screws (with machined ends.. also I have new threads for them in the mount as well).
Now I need a spanner to adjust it, but usually this is not necessary, as I also have a high sensitivity bubble level (glued on top of the original one).
The only thing I have to do now (when/if I am out of my own backyard) is to level it and adjust the South-North direction.
In my backyard, I have 3 concrete slabs (one for each tripod leg) with a hole in them, where the tripod pin sits in.
Proper lubrication of screws also helps a lot.
Ideally, the threads should be replaced with steel threaded bushings, to prolong the life of the thread, if it is to be adjusted very often.
Recently I found this link, it addresses some of the issues:
http://stargazerslounge.com/diy-astr...ment-bolt.html