C-122 sould be C-120 . The V Belt enigma.

While analysing increasing V belt failures, a shocking fact was revealed.V belts are oversized !! We achieve not less than 30 mm deflection upon application of 4 kg with 295 mm long new BTM on new belts !!
Another make tried, same results. That means drawing no SKEL 3940 is wrong. Or belt length of 3150 mm is more than required !So, we cant give prescribed tension even with everything proper. And inadequate tension means belt slippling and consequent failures.
16 mm defection comes on 4 kg when the spring is only 230 mm . Thats as good as no spring.