as i understand this, MOST of the time the amp fails. sometimes however it is the cruise control actuator.
both parts are about the same price. [more than the price of a [single] euro light-bosch or hella type].
believe it or not, the 'brake' light bulbs can affect the cruises' ability to ground itself and not work correctly. i found this on my search regarding cruise control problems.
all the light bulbs in a benz need to be the 'silver' base type.
i don't think this is the problem with your cruise, but for a $2.00-3.00 investment get OEM them. [at the stealership].
the cruise going out is a rather common problem for m.b., not unlike radiator neck breaking, oil consumption, window switches, etc, etc
*92 400e 124.034, SOLD
*92 300e 124.030, SOLD