Replying to P 18 worn out springs

In sure there are other threads on this but I searched and couldnt really find anything relevant. I have two pairs of P 18 (bomber turn table heel) The older pair, this will be my 6th year on them and I bought them slightly used from Mickael Dechenaux (big claim) are starting to get weak. The windows on the heel are broken so to adjust the DIN I count turns. I have a newer pair of identical bindings. I have them both set on 12. On the newer pair this is about right, I eject if I need to but no prerelease nonsense. Now on my other pair (older pair) I turned the DINs up last week and skied this weekend. The DIN was incredibly weak and I ejected out of heels leaning forward on my skis in the parking lot.

I know its not a forward pressure issue.

Could it be possible that when I tightened my heels (I counted the number of turns it took to tighten the heels on my other bindings) they are two loose which brings up the question of the bindings not being identical at least in amount of turns required to reach the same DIN

Or should I slowly turn up the DIN until it feels the same, I dont really want to do this and if I do it will be in slow half turn increments. I have had shop employees tell me this isn't safe but I think it can be if done cautiously. After all DIN is just a measure of spring tension isn't it? And as the springs wear out this number will become relatively lower.