I found these two bugs in circular saw's formspec:
1) If I remove all materials from the saw, the microblocks in left-over
slot disappear. I have to remove the microblocks first and then the
2) If I take a stack of cut blocks from the saw and place it to another
full stack of the same blocks which is already in my inventory, the full
stack disappears and the new stack is placed instead. This works only when
the stack in my inventory is full (contains 99 blocks).
1) and 2)
The handling of items when taking them out is known to be buggy.
The handling is more complex as with other machines/chests, because not all items really available, but will be "made" when removed.
I see no other way beside to completly rework the circular saw with a change of the way it is used. But I think this would need very much work, so that making one or several replacement machines would be faster.
Conclusion: known bugs, but I consider any work at the circular saw as wasted. Please wait for replacment machines.
PS: please don't combine bug reports, write one report for every bug, even when similar, otherwise I reserve me the right to close any bug reports silently with more than one bug without taking notice of the content, because the handling of such reports is a mess.