So what is happening is the deck is moving too far to the right ( sitting on the mower ) causing the left side of the front mount to rub on the pulley.
>>>> Yes, That is the problem. Only happens when you are moving. When I am sitting still I cannot push the deck that far over.
Very first thing is to check that the pulley is the right size, people fit bigger ones to push the blade speed up in the hope of getting a better cut.
>>>>> My Mother is the one to buy it new, And I don't think there has been any modifications to it, except for the mower shop tune ups. And it does not happen to the right mount, only the left side, And only once in a while. But after 10 years it is looking rough. I think it may have done it from the factory.
Next is to work out why the deck can move that far.
A front mount like yours is designed to prevent the deck moving left right while mowing.
I will hazard a guess that the holes in the mower mounting plate are flogged out oval or that plate itself is twisted ( from hitting some thing hard ).
Pull the deck off and slip a bar through the holes in the mower mount and check they are square with the mower.
While the front drag plate is off put a rod through both the mower and the deck mounting holes, they should be parallel to each other if not either weld & re cut them or replace the drag plate.
Similar story with the mounting tabs on the deck itself, although working out square for it is a bit harder.
>>>>> Good idea I will check to see if everything is true.
If it is a 3 blade deck then the distances from the holes to the left & right spindles should be the same . >>>>> It is a smaller 2 blade deck.
They should also be parallel to the blades so support the deck on a level surface with 2 blocks (bricks ? ) under each blade then measure the height ground to mounting holes, it should be the same.
Check that both the left & right front gauge wheels are there , that they are adjusted properly and that the wheel itself is a nice rolling fit on the axel and the axel is firm in the mounting plate.
These items take a beating on ground engaging decks.
Also check for toe in on the gauge wheels, again they get twisted from hitting things and if the left is toed in that would tend to push the deck to the left while mowing.
>>>>> I am drawing a blank. I don't remember any front deck wheels. Will double check tomorrow. And while mowing the deck tracks fine. It is just in a hard turn it rubs once in a while. and only the one side... Thanks for your help.