cenvat credit reversal on export sale of capital asset

dear  experts

suppose  x  company  sells  a  capital asset  t.e machinery  after using  for 5 yeras . then  does the company  have to reverse credit  under section 3(5)  of  cenvat credit  rules  or 3(5) b

how  to calculate the amount of  cenvat duty  to be reversesd/

and  most  importantly  company  is  exporting the machine  to other country

now can it  avail  the facility  on  the basis of export sale of not  reversing the credit

company is selling  machinery undr form h