The biggest issue I see is you're not running Suntour 7-speed cogs. You need a Suntour AP freewheel or the very rare Suntour cassette/freehub. Suntour index shifting will work with 6-speed Shimano cogs but 7's have a unique asymmetrical spacing.
If you got this setup working before, I think it was blind luck. Even a bad choice of chain can throw the Accushift setup out of kilter.