Assalamualaikum,Often during tasleem, I fumble and my 'alaikum' becomes almost like 'alaium'. In the case, if I say 'Assalamu Alaikum' again, is my prayer valid? Do I have to do sujud al-sahw? How should I do sujud al-sahw in this case?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If you fumbled in the Taslim in prayer and you repeated As-Salam Alaikum; then your prayer is valid, and you do not have to prostrate for forgetfulness, unless you got up [finished prayer] before re-saying the Taslim and then you went back and said As-Salam Alaikum, then in this case you prostrate for forgetfulness before Taslim.

Imam Shafi’i said in (his book) Al-Umm: “The least sufficient form of one’s Taslim, is to say As-salam Alaikum. If he misses a letter from it, he returns and says As-salam again, and if he did not do it until he finished the prayer, he returns and prostrates for forgetfulness and then says As-salam Alaikum.

Allah knows best.