Hi,
Most microscopes have some means of adjusting the fine focus tension. It does tend to slacken off with time. Sometimes there is a dedicated adjuster but with some ‘scopes it is done by holding the coarse focus firmly and turning the fine focus. The user manual should tell you, if you have one. You seem to have re-seated the head which was probably not secured firmly, causing the par centrality problem.
I’ve been a silent member of this forum for some time but for some reason I had to register again to post this.
Robbo
