What you have to eliminate to solve a hard start issue?? Well, for WFWIW my approach to solving a like situation with a 190e 2.6. First, you have to know what is involved with the start-up of the car. Studying the circuitry and knowing exactly how it works. Once, you do that, then you can start to eliminate the items to find the fault. It's a task, but with determination you can do it without a lot of tools or investment. I saw where people in some threads I read had replaced nearly two sheets of paper showing replaced items, and it still didn't fix the problem. I failed to fall prey to such a loss of money that way. I did replace the ovp with a new one with 2 fuses. That wasn't the problem however. The big issue I find with the old mercedes even is they are very unforgiving to out of tolerance information sent to the cpu. That can be from replacement parts that were not oem quality. I have now went for 3 months with no fail starts in 1inch or more rain and now 19degree weather outside. You will probably find something, that is a resistive fault causing a lock-out.