Sir yesterday these were taken by a friend and he said he know someone at Brandreth road who can fix them. I said ok you can take them and try. Because the part where it tights is Daigy Loha (Iron alloy). I told him that it cannot be fixed because if he will try to weld it then this Daigy Loha will blast and will immediately develop cracks in it.
But he said he will make an thin iron bush and will push inside it matching the pattern of its threads.
Actually he also does a bit of woodworking like me and said these F-clamps can be very helpful for his projects. He said if he restored them, he will share with me the results in a few days.
Truly very sorry sir 
