Margate manager Mark Stimson believes it’s a mystery why Cheshunt are struggling this season – as the two relegation-threatened Isthmian Premier sides prepare to lock horns. Gate will visit Cheshunt tonight (7.45pm) as they aim to get a first victory under Stimson, which would end a 14-match winless run after 16-goal striker Steve Cawley netted in their weekend 1-1 home draw with basement boys Concord. Margate sit just above the relegation zone ahead of Cheshunt but Craig Edwards’ troops, relegated from National League South last term, have two matches in hand on them. Stimson, whose side retu…