There are several options
Change every transformer for a compatable LED driver
or
HAve one LED driver to serve all of the LED lamps, but that will probably mean a degree of re-cabling
or
use 230v LED lamps and eliminate the old 12v "transformers" altogether.
Its anybody's guess. They mostly come with an average lifetime posted on them. Some have a warranty too.
Some transformers need a minimum load. THESE for instance don't start working until they are ddealing with at least 10watts.
Do the instructions that came with your bulbs say anything about compatible transformers?
Is there anything on the manufacturer's website?
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