Is it obligatory to repeat the opening Takbir (Takbirat al-Ihram) if the pronunciation of the letter "R" is weak, and is one excused for not raising the hands during the Takbir in this situation?

When a worshipper stands for prayer, he should pronounce the usual Takbir (Allahu Akbar) with the intention of consecration (ihram (definition)). It is sunnah (definition) for him to raise his hands. Then, he should turn away from all other distracting thoughts and not pay attention to them. He should proceed with his prayer normally, and not repeat the intention, the Takbir, or the raising of the hands. Scholars have warned against obsessive doubt (waswasah) regarding pronunciations, as it is a deception from Satan.