[morzh]

So you have Run 2? Are you sure?

So, it has variable slug instead of the padder. Is this what you have? You move the slug and not trimming the variable cap?

If this is the case, you simply do not know, whether you cannot get the inductance low enough or high enough to peak. So you need to see, whether the slug goes in the coil, or out of it. If it goes in, while the signal is increasing, then you need to increase the cap. In this case you PARALLEL the small cap (5-10% of the existing cap value) across the cap that is there (again, the cap is not variable if you have that Run 2).
If however your slug is going out of he coil when you are peaking, while the signal is increasing, you need to DECREASE your cap. This is achieved serializing another cap with the existing one. The cap has to be about 10x larger than existing one: this way you will reduce the capacitance by about 10% or so.