I believe they had a certain amount of corrosion repairs done in the late 80s. Following a deep strip and discovery of corrosion in a civilain 125.100 (IIRC) inspections of the RAF fleet was done. The lower hull under the floor and also up under the toilet were found to be heavily corroded. I looked at one aircraft where the Abingdon repair team were working at Finningley writing a repair plan.
The fleet was also re-winged in an interesting and innovative way. It is true to say that no Dominie flying today is the same aircraft that left De Haviland's factory.
An aircraft was flown to Aberdeen where BA Helicopters removed the wings, stripped, re-sparred and paineted and reassembled them. The next aircraft was flown up, its wings were removed and the first set fitted in their stead. Its wings were then refurbished etc etc.
Yes, same engines. Noisy? Not at that size. Fuel efficient, certainly not. In the 60s we used to fly for about 3hr 25 and I think I did 3hr 40 once. In the 80s the trips were down to 3hr and times rarely exceeding 3hr 15. Once the low level syllabus was introduced the sorties were shortened to 2hr 30 - 2hr 45. Quite long enough at the more demanding activity levels of low flying.
During its time minor updates were made to the nav kit, a magnifier and a mechanical cursor was fitted to the Echo 190. One GPI 4 was swapped for a TANS. A DME was fitted. Small beer.
The nav kit was comprehensively updated in the 90s with, I believe a new radar too and also a new seating lay-out which marked a major departure from the 1960s V-Force layout.
Initially bone-domes were worn to get the student used to working with a hard hat. By the 90s everyone wore light weight headsets. Practise bleeding could come later.