I have been asked how I lower my Farish 37s; I hope this helps explain it. Descriptions are in each photos caption. It's not that hard to do but worth it in my opinion. I've never had any issues with running but I don't use settrack curves, and obviously anyone following this does so at their own risk!
Comparison between modified and unmodified Farish Class 37s. I also painted the visible brass bits of the pickup strips black whilst the loco is disassembled.
Body off and cab interiors removed - these just pull out. If anyone needs any I have about 12 in my bits box now!
The contact board slides up and out of the chassis: careful not to break any solder joints. I have painted 2 white dots onto mine above - file this away. It's about 2mm, about half way up the brass circles under the lighting contacts. You're basically extending the cut out. It's important that both sides (and ends) have the same amount filed so the body sits level. They then just slot back in.
Chop the lugs off the battery box; this will no longer clip onto the bottom of the chassis block. I fix mine back on the chassis with blue tack, but you could use double sided tape if you prefer.
Reassembled, it'll look something like this! I hope this helps anyone looking to do a similar mod.