Repairing MF MC-2 - low output on one tweeter

[KennyK]

I've recently acquired a pair of Musical Fidelity MC-2 Loudspeakers, with the intention to put them in my dining room system. One of the tweeters seems to be working better than the other. I want to have a go at reparing these, but as it's my first attempt at tweaking loudspeakers, I'm not sure where to start.

is it likely to be the tweeter that has started to fail, or something in the crossover?
if it's the tweeter, I'm not sure where to start in my search for a suitable replacement, so any help in selecting something approximately similar would be appreciated. In fact any tips as to how to go about getting these back to working condition relatively cheaply would be good. I'm not fussed about them sounding exactly like a factory fresh pair of MC-2s. both sounding the same and approximately right would be enough.

the Bass on these seems to be quite good. it's just a shame that the treble on one is a bit quiet - the tweeter does seem to be working but low output. I've not had a proper look inside yet, but it's 4 screws to whip the woofer out to get access to the innards.