I should check? 10cm depth

[Tekeweke]

my tgsl detects a coin and something bigger 6cm to 10cm that I review to increase its depth TX works with 200mV is only for the moment that I can measure, I'll have to change the value of some capacitors and the coils are made as is detailed in the post.
some days will have an oscilloscope can someone tell me what points should I test the pcb could point me in the scheme
thank you very much.