naunihal singh , 54 , woke up great-grandfather ujjal singh , 63 , and slashed him with a kitchen knife at his son and daughter-in-law 's home .
the attack in crumpsall , manchester , came after a heated argument over the couple 's lack of children - with ujjal accusing naunihal 's son yawinder-pal ` monty ' , 37 , of ` firing blanks ' .
today , naunihal was jailed at manchester crown court for at least 17 years and 39 days after admitting murder .