Original secondary winding:
sw
 yl (twin):
1.3
Ohms
yl (twin) 
gr (right):
5 Ohms
gr (left)
 br (left):
7.4
Ohms
br (right) 
yl (right):
7.4
Ohms
yl (left)
 rd:
6.3
Ohms
Conversion to 25 Ohms
secondary:
1.
Solder the two
windings in the yellow isolation together and isolate them
2.
Parallel the four windings you get taking care of phasing. All reds
from the picture and all blues have to be soldered together.
