I posted in the tech forum as i have also had problems adjusting the tension bolt. To add to this ive just found out that Strida i have is in fact a fake one; a Ming Tai.
Does the Ming Tais have the same C-spanner tension adjustment?
Ive just noticed that Ming now own Strida so it is an official one??
Well ive looked through this post and used a hammer and screw driver to knock that BB back. Nice tight belt 
Sorry for bringing up at old thread … on my strida 5, i managed to loosen the ring but still not able to move the nut to loosen my belt tension
Any other suggestions?
No reason to be sorry 
If you loosened the “ring” (equal to lock ring, groove nut or the part 5 in the rectangle 130-00 shown at the detailed parts drawing, page 12 of the manual) - which part do you mean with the nut?
Strida manual
Hi,
I was trying to slide/move part 274 after loosening part5 of section 130-00.
No matter what i do …the screw 274 does not move in any direction
Hello RLCH,
please try it like that:
Remove bolt 274 completely, after that insert a drift punch into the thread and move the bottom bracket excenter:
(Disregard the arrows and the Allen key shown below.)
Caution: Do not insert the drift punch too deep at ATS or Schlumpf speed drives - otherwise you might damage the shifting axle which is located inside of the bottom bracket axle!