Brother KRC-800 color changer is identical to the Brother KRC-830 color changer. Thus, read a blog article I wrote on KRC-830.

Brother KRC-800 color changer is designed to work with the double-bed (standard-gauge knitting machine + ribber). The range of knitting machines compatible with this ribber is from KH830 and above. The ribber that will work with this color changer start from KR830 and above.

I suspect the main difference (with the obvious exception in the model number) is that KRC-800 was released to the Japanese market only. Thus, its manual, even though it is identical to KRC-830, is in Japanese.