Fuel Tank Senders

[Kipstone]

Fuel Tank Senders - Centre Consul 23 Foot 1976
Please help if you can!

Has anybody got the best suggestion to accessing and the exact position to both the fuel tank senders? Both my Yamaha senders were incorrectly installed - both guages showing opposite to actual state ie full when empty, not a good thing especially when I did not know this when purchased!

One guage has now stopped working completely - so the senders being faulty or installed to the opposite polarity are probably the reason. As its a centre consul its going to have to be a de-rig to access the tanks and I want to find a permanent solution. Has anybody got experience and advice on cutting access hatches above the tanks to access the senders? If so, can you still locate original castings for these new hatches that match my current 1976 patterns?

Any photos for guidance or technical advice for location, remediation etc would be most gratefully received as this boat is now located in the UK where obviously Seacraft experience & knowledge is non exsistant - I think my 23 foot Seacraft is the only one in the UK (good to hear from anybody else in the UK if not).
Many thanks in anticipation
Chris