Can any one help my boot catch has jammed.I took it apart and I think the spring has gone. do i need to buy the whole unit including the plastic cover and what the best way to refit it .It looks complicated fixing it back to the rods etc

is this a weekend? if so the problem is the spindle the catch flap pivots on and the flap sticks in the up position; this is carbon steel not s/s and corrodes; after dismantling lock you can access this but seems impossible to remove but can be moved back and for slightly to free it used some acid rust remover also then greased it; problem recurred after 2 years so repeated procedure and also drilled hole in flap and fitted a short length of nylon string to pull it down.....