Any Advise On SJ410 Trip Counter/Meter Repair?

[SherwoodNash]

'Just picked up my SJ from local garage where it had it's MOT.

The trip meter was set to zero and working perfectly when dropped off.
Now showing random numbers which don't respond to any amount of pushing and fiddling

I find the trip counter very useful so would definitely like to repair.

So it'll be steering wheel off, shrouds removed and column lowered to get the speedo cluster out.
Once there, is there an easy route to fix this part or is the back of the unit all sealed up plastic?

Thanks,

[SherwoodNash]

I found this eBay pic of the back of a JDM Suzuki Sierra which would be very similar to mine, disassembly looks tricky?