First Tony Crane was ruled out for the season, then Rob Jones for six weeks and now Downey - although no length has yet been put on his recovery.
That leaves Slade with just Justin Whittle, Simon Ramsden, Greg Young and Kirk Wheeler as fully contracted centrebacks. Week-to-week man Dean Gordon is likely to start at centreback again this Saturday against Rushden & Diamonds.
Town's second string lost the game 3-2, with David Soames and Graham Hockless (penalty) on the scoresheet. Margate Town striker Darren Watson got a third chance to impress Slade whilst former Swansea defender/midfielder Andy Mumford was given another run out.