Autohelm 800 power transistors

[winater]

Hi,
Our trusted Autohelm 800 started a mutiny, and after opening her up the problem appeard to be fried power transistors.

Two of the four transistors on the position TR4 and TR8 were fried beond recognition
the others were;
BDW 93B 8923 on position TR7
and
BDW 94B 8917 on position TR 6(?)

My question to the gathered wisdom here is; what were the typenumbers of the unrecognisable transistors?
Bonuspoints question ;-) whith which type of transistors could all four of them best be replaced?