I have effacement of nearly all csf around nerve roots in my spine. should i still be doing my heavy manual job.

Depends: Spinal stenosis is a condition in which there is narrowing of the spinal canal leading to, as you put it, "effacement of the CSF around the nerve roots in my spine." it is not a dangerous condition and its presentation is quite variable. In general, patients occupation activity level should be such that it does not repetitively cause pain, regardless of what their MRI shows. Thank you.