1996 E230 ETS/ABS warning lights on!

[EddieRooster]

Hi there. About a month ago my MB wouldn't start after a warm stop. But it then seemed to right itself. On Wednesday after driving out of the garage, the ABS/ETS warning lights came on. Took my MB to MB auto-electrician on Thursday - diagnostics number (?) said that problem was in/at the brake light switch which has a ratchet adjustment??? This was reset and adjusted by MB AE. Problem was fixed for 2 days. ETS/ABS warning lights are now back on again.
The tyres are all the same size and pressure.
could it be the K40 - is there one in this car?
or where/how do i find this problem brake light switch?
Any advice welcome! Thanks Peachparts. Ed.