The 'slop' is there to help you adjust the guides so the blade cuts vertically.
The adjustments interact somewhat, e.g. the gap between bearings should be 0.002-3 bigger than blade thickness.
Then adjust blade vertical at both guides, check with test cuts in hardwood.
Then adjust vise perpendicular to blade.
There are further details in the document referred to earlier in the thread.
Better, i.e. machined instead of stamped, washer under those SHCS might help prevent movement in future. If the threads in casting are stripped you should be able to go up one size.