I am giving my 1995 marzocchi dh3 forks an over haul and need to know everything about fork oil level, air pressure, sag setup, how to disassemble and reassemble all seals I have no owners manual

open the screw and with a siringe you flush it until you reach level

There are severall answers to this question (with videos) if you use a search engine for "rebuild marzocchi xc fork". You can get creative with the search terms.

As far as parts availability is concerned, scour the web (search engines again) or eBay.

Maybe hit the marzocchi site, register and ask them or search for documentation.

https://www.marzocchi.com/Utenti/login.asp?LN=UK&idC=1580&URL=%2FUtenti%2FSupport%2FDefault%2Easp%3FLN%3DUK%26idC%3D1580

The best thing to do is take your forks into a bike shop that works on suspension and have them take a look. It could be low on oil and/ or air and bottoming out or it could be something more serious.

If you know the year of the fork you can pull an owners manual from the Marzocchi website. They keep a running inventory of all their manuals in PDF, this will also help to diagnose the problem and let you know what you will need to overhaul.

I would suggest you visit www.marzocchi.com and go through the tech section. There are manuals, videos and more on your fork. It is good to know not only the basics but regular maintenance schedules and when to take into a shop for an overhaul.

Specifically to add pressure you need a shock pump to add air. Going back to the website reference they will tell you how much for the type of riding yoiru doing and your weight.

You may have an air adluster, schrader valve with which to add air pressure, or there may be settings on the rebound and damping settings, are the fork seals leaking oil at the sliders of the forks, springs do wear out as well, some bicks have anti dive solenoids activated via front brake activation and limit the compression of the front forks upon rapid braking, , you maty need springs, seals and thicker fork oil its hard to say exactly what you have going on but its one or more of these.

This is most likely not the answer you are looking for, but I would highly recommend taking these into a bike shop that has experience with the Marzocchi's. These are fairly complicated and require some speciality tools, and extremely easy to do damage that will be an expensive fix later.

First red flag is that the rebound screw does not move. A fork overhaul is probably in order, replace the seals and oil, check all the screws too make sure they are not stripped, adjust the air pressure, and so on. The bonus is a shop that can perform this overhaul, will also be happy to show you how to maintain the fork and how to adjust everything properly, and if you don't have a fork pump, sell you that as well. Trust me, these can be challenging without knowing exactly what you are doing, I am highly trained and I still have issues now and then with Suspension Forks.

I have included a video with a Marzocchi tech guy explaining a slightly newer version of your fork, Yours is basically the same.

Here is the link to the Owners Manual for your fork. If this is not correct you can get any manual for any fork they have made off the Marzocchi website under tech.

loosen top pinch bolts loosen caps remove forks remove springs , fill according to manual level . re-instal everything .,,,

loosen top pinch bolts loosen caps remove forks remove springs , fill according to manual level . re-instal everything .,,,

loosen top pinch bolts loosen caps remove forks remove springs , fill according to manual level . re-instal everything .,,,

ZERO air pressure on these forks those air valves are to get rid of any built up pressure in the tubes. I also have a 1990 851 love it! What weight of oil are you running and how much are you putting in?,,