Hi Bob - you've been nibbled by the 'sectioning-bug'!!
As suggested above, I would go a step further though. Put the block into some molten wax of the kind you're using and wait for it to melt completely, at which time the moss will become visible in the liquid wax. Then, simply pass the shoot through say 3 firther baths of new (molten) wax (perhaps 3 hours each stage). This should be enough to displace/replace the old wax throughout the tissue and enable a fresh re-cast of the moss shoot tobe made. This technique definitely works.
When I go to the embedding phase with my tissue, which will of course be in it's final infiltration wax, I cast as many blocks of the tissue I desire, and am invariably left with lots of pieces in the infiltration wax that are simply 'too good to be discarded'. That's where I cast one or two of what I call 'bulk blocks'. I simply dump all the remaining pieces into large blocks and let them set in the usual way, no orientation - just storage.
At a later time I will re-embed (the tissue is already thoroughly infiltrated with wax) and reorient of course for the cut desired, into new blocks.
With your old block you just need to add the extra wax baths as you are going to re-infiltrate the tissue (moss) as well as re-cast the block....
Aha - found some images of bulk-blocks for re-casting from slide making at the beginning of this month,
link to dandelion root bulk block and
link to coleus bulk block
and
link to re-embedded sonchus stem tissue
The coleus tissue, initially cast in 58 deg wax, was not sectioning very well, so I re-infiltrated and re-cast it into 52 deg 'Paraplast +' - from which it has sectioned very nicely. Don't be afraid to re-cast or re-infiltrate and cast - it can save what you may have thought was a poor tissue, or be very good if you need to re-orientate for better sectioning planes.
