one note about the problems you are having getting your gears to work properly

bikepedia says the 2007 raleigh venture 3.0 has 7 speed shifting on the rear
but unless i am missing something you only have six cogs on your freewheel
so either the freewheel or the whole rear wheel was replaced

if you still have the original seven speed shifters
you are likely going to have trouble ever getting it to work acceptably