I took the plunge today and took the FL1 to have the codes read. The prob I've got is that after fitting a replacement clutch I had the 3 amigos

Managed to get 2 of them to 'go' but was left with the yellow HDC lamp on. I've recently replaced the suspect ABS sensor [FLH] and that brought the 3 amigos back!.
The code reader showed that there were a lot of historic codes which were cleared. The mechanic is experienced with LR but hasn't encountered too many FL1s. Codes suggested a possible FLH ABS issue.
So my question is: when installing [or refitting] an ABS sensor what gap should there be between the reluctor ring and the end of the sensor? I used a small piece of plastic about 1mm thick - slipped that in-between the ring and the sensor, pushed the sensor onto that plastic the tweaked it back a wee bit and then removed that piece of plastic.
Is that gap critical? should the sensor be closer to the ring or further back?
Do we lube the sensor and the copper cage prior to installing?