Suggestions for stretching turntable belts?

I have had a great deal of dificulty finding TRUE 35.1" turntable belts (as used by Sota,the Luxman PD 300,B+O 4002/4004,the Empire tables and some older Pioneers.I have gotten them from many sources- PRB,Ebay,etc. and they all seem to measure about 34".Needless to say with a floating subchassis table this will not work as it pulls the platter toward the motor spindle.In some cases it will even jump off!Is there a good technique to uniformly stretch these? I have even painstakingly cut the belt in half length wise with an exacto knife to try to reduce the tension.
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I remember buying two belts (or was it three?) from different sources for an AR ETL ONE and not one of them worked properly. I wouldn't be surprised if there is quite a bit of hit or miss with aftermarket belts and can only suggest you try one out from a different source. If SOTA uses that length it may be a good idea to pay whaeever it is SOTA asks to get one. Good luck.
I had similar experience as Pbb - and Tim and Turntable Basics was fantastic. I had an unusual situation - and he ended up sending me multiple belts - he said "send back the ones that you don't need". This is for a $12 belt! I wish I had that level of service for expensive gear.
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A work around of course is to use your tt "pitch" or fine speed control with a strobe to compensate. Stretching is definitely not the answer. If fact, a good argument can be made that a stretchy material is not appropriate for a tt drive belt.
Hi,thanks to all for your advice.Swamp,the issue is not the pitch/speed,it is that it disrupts the floating motion of the suspension as it pulls the platter closer to the motor.On a fixed suspension table this would probably not be an issue.I would like to know where Sota sources their belts from as I have four tables that use this size belt and can't bring myself to pay the $25.for each belt.Call me cheap,but if someone knows where I can buy these at a reasonable price I will buy a dozen!