Hi
I have done 2 or 3 of these with Massoth XLSounddecoders,
It is fairly simple, The existing onboard PCBs can be discarded as the decoder does all the nescessary functions, simply identify the 2 sets of pickup leads, from each bogie, link these together ensuring that you get the correct pairing ie left hand rail & right hand rail!!
Similarly identify the 2 sets of motor feed cables and link these together ensuring as above you get them correctly paired!
From memory the cables for the above are coloured Brown, white , green & Yellow., white & Brown are pickup leads ( from track) Green & Yellow are motor feeds
This infor is contained in the Massoth decoder instruction manual.
Then a lead from the front light goes to connector mark LV similarly rear light goes to connector LH. and the other lead from the front & rear lights go to connectoor marked +
Cab light is wired to L1.
Again this is clearly marked in the instructions.
It sound complicated but working methodically from the decoder instructions is fairly easy AND the Saxon is an easy loco to get inside of!!
EDIT: Just re lookng at yr pics it is poss that the loco's wiring from the bogies ( th 4 wires which on some locos are colored yellow green brown white may not be coded this way so it will just be a case of checking to see which of the 4 wires does what which can be done with the 2 leads from an analogue controller or a meter if you have one,
Your loc is a 2001 manufactured one and there were some wiring changes made in LGB production around this time.
Good luck
