Sounds about right for a failed unit, but I would double check this, I had one that failed and it pegged at 3 bar, this is on a 85 190E 2.3L 8vlv, not much different as far as I can tell.
Replacement is tricky, I didn't bend wrenches, I took off the whole oil gallery with an extension, then when it's out removing the sender unit is a walk in the park, but the bent wrench idea sounds good also
Let us know how it went and how you bent it exactly.
xp