I'd splice the wiring back even temporarily in case you've cut a common return to the decode. I can't remember the 071 wiring diagram and although I have both these locos I' haven't looked inside in years so take this advice with a pinch of salt for now.
8113 has 4 newer LED markers. Iirc, the four prisms enable the light to be refracted to the outlet but I can remember where the LED diode is. They're usually covered in black plastic to limit light leak. The older 3-marker arrangement would refract from either a white or red diode but since they have separate outlet , it does seem like there should be a third prism for the red marker....
Looking in the DCC section forums may be of help
I'm sure you'll have seen the basic description and specs on Wikipedia
BNCR Class N
Type and origin
Sharp, Stewart & Co., Manchester (No. 42)
NCC, York Road Works, Belfast (No. 16)
1874 (No. 42)
1914 (No. 16)
5 ft 3 in (1,600 mm)
4 ft 0 ⁄8 in (1.222 m)
7 ft 9 in (2.36 m)
25 ft 3 ⁄8 in (7.70 m)
8 ft 4 in (2.54 m)
11 ft 11 in (3.63 m)
13.80 long tons (14.02 t)+
17.25 long tons (17.53 t)
31.05 long tons (31.55 t)
15 long cwt (760 kg)
600 imp gal (2,700 l; 720 US gal)
130 psi (896 kPa)
661.12 sq ft (61.420 m)
590.88 sq ft (54.895 m)
70.24 sq ft (6.526 m)
16 in × 22 in (406 mm × 559 mm)
No.42: Hand brake
No.16: Steam brake
12,707 lbf (56.5 kN)
Factor of adh.
The Five Foot Three reference might yield some assistance. I don't have a copy but someone else might ...
Scott, W.T. (January 1968). "The Shunting Tanks of York Road". Five Foot Three. 4: 2–10
I am an early to mid 80s' man up to Mk 3 era so am really interested.
Haven't ordered yet as was waiting to decide what to do so I will definitely buy 2 plough in CIE finish.
Likewise with the Tara's I have held off. Not so much by the colour but by the roof.