Hi Hess
First part of your description ressembles like a shart circuit: "just got a BR50 (33840) delta 33 with 4 dip switches when it makes contact with power track it stops all locos however it don't activate stop mode but all running locos stop if i press stop then light on ms2 goes red". When detecting a short, the MS2 cust to power but does not lit STOP (only when you press on STOP, still no power but now STOP is red.

"the second time all traffic start running the driving lights are on when train is moving and will not switch of old style light bulb im thinking to remove bulb all other loco's and delta loco will run over this track section ok" Here I am not sure but it looks like the current peak is now OK and that your Delta loco is set for analogue operation.
Check the manual for switch setting DONT do gess work. Your decoder could be a Märklin 66031 To be checked but I cannot find the user's manual

Here is what I believe are the setting for the 4 switches:
- only 4 digital addresses are allowed (blue arrows)
- one analog prosition (pink arrow). Digital won't work in this position (when all switches OFF).

Cheers
Jean