Kindly enlighten me of the ashtakshari mantra and the way how it has to be chanted. Since I did not know the value when samasrenam was done some 30years back as a ritual soon after the marriage. with pranam to the lotus feet of swami lakshmi

Jai Srimannarayana!
If initiation is taken then after chanting the Guru Parampara, ashta:kshari manthra may be chanted. There is no swara or specific way to chant it. Chant it in a normal way, not too fast nor too slow. If possible try to recollect the meaning of the manthram. That given a lot of benifit than just repeating like a parrot. You can just start it after taking Sri: pa:da thi:rtham.