Access Increment special numbers in an access query

[espensu]

Dear all, I wish to create an update query that convert/renumbers present string to a new format.
Typical current format in text fields:

UGR, JOB
382.05.06, 382.05.06.02
382.05.07, 382.05.07.01
382.05.07, 382.05.07.02
382.05.08, 382.05.08.01
382.05.08, 382.05.08.02
388.02.01, 388.02.01.01
388.03.01, 388.03.01.01

I wish to achieve that it renumbers by row sequence when grouped on "UGR":

NEWUGR, NEWJOB
382.001, 382.001.02
382.002, 382.002.01
382.002, 382.002.02
382.003, 382.003.01
382.003, 382.003.02
388.001, 388.001.01
388.002, 388.002.01

Have seen similar requests on the forums, but can't seem to create one that works for me. I would prefer to do this in a query, since I mainly work with manipulating data in tables (and not forms).

Thanks,