Update:
I seemed to have fixed the problem (fingers crossed). There was no particular notch for the spring on the LHS of the mower for the #21 spring. Absolutely none. However; I found a hole in the frame on the LHS & stretched the # 21 spring to there. This increased the tension on the belt & the mower is doing much better. Due to increased tension on the # 21 spring I noticed the other extension spring #24 came off while mowing. The mower seems to be running fine without it; just curious your thought on replacing it. If I do I will need to bend the ends of the spring to keep it from falling again.
I seemed to have fixed the problem (fingers crossed). There was no particular notch for the spring on the LHS of the mower for the #21 spring. Absolutely none. However; I found a hole in the frame on the LHS & stretched the # 21 spring to there. This increased the tension on the belt & the mower is doing much better. Due to increased tension on the # 21 spring I noticed the other extension spring #24 came off while mowing. The mower seems to be running fine without it; just curious your thought on replacing it. If I do I will need to bend the ends of the spring to keep it from falling again.