Rev counter and econometer not working

[BigDave1]

Advice please. I have an '89 325i Sport. I noticed both gauges (Rev counter and econometer) not working last week. All other gauges and light are fine. I replaced the two 7.5 amp fuses in slots 10 and 21 of the FuseBox (the one in 10 was blown) but no change? I have now removed the SI board from the instrument panel (it's the later shiny type with orange arrow sticker and the shorter, Sony Lithium batteries). All seems fine inside and there are no leaks from the batteries, which are showing 2.83V and 2.84V when tested. What should I check next? Thanks, BD1.