Sony MD machines use a 1.0mm pitch FFC cable between the main PCB and the MDM.
eBay seller (UK) (As of Mar/2020 they are around 2GBP per 2 pieces from China)
ETA (Oct/2020):
Above link is broken. Seller in UK is hkdz-2017: http://www.ebay.co.uk/usr/hkdz-2017?_trksid=p2057872.m2749.l2754
This is his shop, searched for FFC 1.0mm: https://www.ebay.co.uk/str/hkdz2017?_bkw=ffc+1.0mm
If the size you want isn't listed, ask him - some of the sizes I wanted I couldn't find. I asked him and he pointed me to another link.
Cables listed below may be the same for machines higher in the same range (e.g. 440,640,940). Check the Service Manual for the same Sony part number in each.
MDS-JE480 (MDM7S1A)
23P, W=24mm, L=80mm, Forward
27P, W=28mm, L=200mm, Forward
Front panel: 15P, W=16mm, L=150mm, Forward
MDS-JE440 (MDM7A)
23P, W=24mm, L=80mm, Forward
27P, W=28mm, L=80mm, Forward
Front panel: 15P, W=16mm, L=290mm, Forward (use 300mm)
MDS-E10, MDS-E12 (MDM7SC)
23P, W=24mm, L=195mm, Forward
27P, W=28mm, L=165mm, Forward
(Above are non-standard sizes, choose 200mm product and fold accordingly.)
Front panel: 23P, W=24mm, L=80mm, Forward
More as I find them.
Kevin