Why not use belts form CPC ? they sell a vast range of sizes for both walkmans and stereos.

They sell packs of belts with lots of different sizes and for cheap. They even do a pack for walkmans with small belts and varied sizes in the pack. I'm pretty sure you will find a suitable belt from there.

Ok, good luck then

As much as I hate marrs stupid prices, he belts are top notch, he never been wrong, been correct specs everytime, usually use him for tapedeck belt kit. 

Go thur his site, it alot cheaper $19.00, which it still a ripoff, the shipping I would just email him. The problem is he will use a box, instead of just the padded envelopes, which I don't get, as it just a belt and trys to make money off of shipping. He would get alot more bussiness if he took off 5 bucks off the price.

The other guy I use is "parts-vintage-electronics" he alot cheaper, but doesn't always have the belt, you have to ask.

Have a word with Doc P. He is a Walkman belt expert and will advise as needed. He is very  reasonable in every sense . I got a whole pack of walkman belts (15) with Doc even biasing them so there were more larger sizes for $21 which may have incl P&P. Once you hook up with him it's unlikely you'll need to go anywhere else.

701c uses a common belt size vs other logic sony walkmans. I remember making similar mistakes with mechanisms I am unfamiliar with- especially the TPS30. That is a nightmare.