I've acquired a new IR2153 and desoldered the original unkown driver and as
the Tx primaries are some distance from the driver IC, soldered in a turned
pin socket. The old one has Thailand and R3 mould marks on the underside and
perhaps the second line on the top starts with a 7 and the third line ends
with a 5 . I'm assuming there was a top line that is well ground out.
Will power up with a couple of droppers in there with 60 percent mains ,
still set on 240V jumper.
I can now compare old and putative replacement