Hi Plantmark,
I cant see from the image how slimey it is but from your description and previous photograph this manure has not completed composting and is as I suggested too fresh. Properly composted Horse manure has little or no evidence of the straw remaining which is why I suggested, based on the original photograph rather than your assertion that it is 9 months old, that it is still too fresh
I only use Horse manure myself and in my experience it needs a minimum 12 months but preferably 18-24 months of composting depending on how and where it is stored by the Stables. The storage method is very important – hard surface and covered from the elements.
I think your only option is to dig it out and return it to the compost bin.
Don.