Thanks for the replies guys, Mark, I am familiar with the idler arm you've mentioned - actually, the play in all of the components were closely looked over - I removed the entire deck from the tractor numerous times, and have replaced all of the pulleys and associated hardware with sears parts (from the sears ordering system) ?
the idler arm has "maybe" 1/16th' play, hardly a wiggle, you think its worth removing this again...? i'm hopeful possibly the belt size might be the issue...