Do you find that the more you try to relax and 'let go', the stiffer your muscles feel? Or perhaps when you try to make small adjustments, the rest of your structure is pulled out of alignment?
A change is as good as a rest.
You might be trying too hard! If you are working at the edge of your current ability, it can be difficult to know whether you are trying too hard, or not trying hard enough. Also, if we are impatient to feel a change or a 'result', it can be tempting to try and 'force' things to happen, even 'just' a little bit. Of course we have to try, and in our search for the optimal approach we sometimes do too little, and sometimes also too much.
The solution to this sort of problem sometimes lies within a deficiency in other aspects of your practice, which may be blocking your progress and will need addressing before you can move forward.
So, perhaps instead of struggling on blindly, or giving up in frustration, you could try a change in approach by working on other aspects for a while. For example, refining your balance and the maintenance of your alignment (centre of equilibrium) will make it easier for you to relax and, in due course improve your ability to feel your internal connections, leading to greater precision and effortless adjustment. Now you can return to your previous work, and move forward.
If we don't try hard enough, nothing is achieved.
If we try too hard, or are too insistent, then it leads back to stiffness.
Wee Kee Jin speaks about this, and so did his teacher. Wise words I think.
Leon C. Megginson paraphrased Charles Darwin thus: According to Darwin’s Origin of Species, it is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust to the changing environment in which it finds itself.
Paul Fretter, Norwich, UK