Thank you all for your contribution.
Thank you Antinn for your suggestion. I cleaned the record again with distilled water only. But the problem keeps there. I believe the grooves are damaged for good. Regarding your suggestion that an existing detritus got removed and showed the problem, all my 12” records were cleaned at least once, more than a year ago, with my late,Audio Desk machine, which broke the pump. It is very unlikely that some detritus was there, IMHO.
but I made further actions following your advice. I decided to clean another record (old and with a new spare copy) with the distilled water ONLY. After a listening, I didn’t hear anything remarkable. Then, I put again on the tank the old mixture of water and cleaning solution (which I kept on a bottle for my dealer analysis). Listening again, the problem WAS THERE. It seems the problem is on the mixture. I remember when putting in the 3 drops, the last one might have been doubled. However, if one drop has this effect, it is concerning.
As the distilled water was old ( more than a year not sealed but closed with its cap) perhaps the problem is there, although a doubt.
I will do another experiment with the old bottle of distilled only and let you know.
Regarding some comments of not disclosing the OEM, I do think when someone puts an atomic bomb opinion on a forum like this it might be very damaging for the particular OEM, so I like to be prudent and respect other people efforts and investment in their products. At least until I spoke with them and get proper customer care.
My old machine was an Audio Desk, which had a pump problem and is impossible to repair because the machine is sealed. Audio Desk offers a new one for half price with return of the original unit. However, it still gets expensive, with no assurance that the e pump won’t break again in the next years. With the audio desk I never had my problem at all I cleaned more than 1000 récords.
the new machie Brand was añready guessed by some of The members, but please dont jump with conclusions. I Will keep you informed of further progress regardisns the distilled water or The “overdose” ou cleaning surfactant.