I'm not Fred but that has never stopped me from jumping into a discussion to add my two cents. :roll: Others may have different opinions but I think servicing your front forks is necessary every two years or 20,000 miles intervals at the very least. Doing it more often is not a bad thing and every time you do it you should feel a definate improvement in ride quality if you have at least 10,000 miles since it was done last.
If you are talking about a stock Honda front end, there is no "shock absorber" in the strictest sense of the word. There is a dampening rod in one leg and a dampening valve (cartridge) in the other. If you have been "Traxxionized", then you have cartridges in both legs. The left fork leg also has an ADV (anti-dive valve). I expect that Max from Traxxion will jump in here to "clarify" the terminology I have used but I think it is accurate enough for this discussion group. If you want a full blown tutorial on Gold Wing front forks (along with a passionate sales pitch), go to the Traxxion site and watch Max's video.
I will not say that there is anything wrong with the Traxxion suspension because it appears to have been well engineered. I will say that I could not justify its cost so I went with the Race-Tech Gold Cartridge Emulator kit that I installed myself. Excellent bang-for-the-buck in my opinion. If the stock Honda suspension works well enough for your riding style, then just service it regularly and you should be good to go. Just ensure you replace any wear parts when needed and don't just replace out the fork fluid and think that is good enough (IMHO).
I replaced my fork springs with the Traxxion fork springs and it works for me.
As for how worn your front forks are, you would have to contact a dealer and ask what the suspension should be when new and then measure yours. That way you will know how much "sag" the front fork springs have changed.
I agree the front fork oil should be changed every 2 years or 24,000 miles. Same goes for the coolant and the clutch and brake fluid change. Easy to do and makes a world of difference.
Depending on the load you carry on your bike, you might consider some aftermarket springs... Also if you want to play with the dampening a bit, then you could try a different weight oil as well... I haven't messed with my 1800 as yet (racetech springs have been ordered though), but on 1500's and 1200's I liked using 15# oil vise the 10# called for... I tend to prefer just a tad stiffer feel but not too stiff...