Floor Jack Tuneup Question

I would like to try to tune up my floor jack before giving up on it and buying a new one. It works, in that it lifts my vehicles and holds the weight with no problems, but it seems like it takes more pumps than it used to. Each pump only raises the jack about a 1/2" and the handle has to be pushed almost to the ground to get even that much.
As can be seen in the link below, there are 3 plugs associated with the cylinder:
A screw plug, covered by a clear plastic disk. I think that may be the air bleeder plug.
A hex head plug, which I believe is the fill hole.
A rubber plug in the middle of the cylinder whose purpose I do not know.
I watched 3 different videos on how to bleed a floor jack. Each one showed a different method. One said to remove just the air bleeder plug, another said to remove both the air bleeder and the fill plug and the last one said to just push the rubber plug to the side and the air will rush out. (They all said to loosen the handle and pump the jack to bleed it.)
What is the correct procedure to bleed (and possibly fill) this jack?
http://i440.photobucket.com/albums/qq121/DerbyDad03/Floor%20Jack_zpslv5ccgq3.jpg
Thanks!
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On 03/06/2016 08:18 PM, DerbyDad03 wrote:

Pressure valve first
Fill plug second
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On Sunday, March 6, 2016 at 10:39:27 PM UTC-5, philo wrote:

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On Sunday, March 6, 2016 at 10:39:27 PM UTC-5, philo wrote:

Could you be a lot more specific? As noted in my OP, I made assumptions as to which plug is what. I'm not even sure I got that right.
What is the exact procedure from start to finish?
Thanks.
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On 03/07/2016 05:56 AM, DerbyDad03 wrote:

X

Unless anyone here says different, just open them both .
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On Sun, 6 Mar 2016 18:18:00 -0800 (PST), DerbyDad03

Every one I've monkeyed with the rubber plug was what you removed to "fill it". Let the jack all the way down, pop the rubber plug out. If it's like mine it will be on "top" so to speak when the jack is flat down on the ground. Pour hydraulic jack oil into the opening till it's filled. Put the rubber plug back on. Best to leave it a little underfilled to allow for heat expansion. If it's too full and it warms up it might pop the rubber plug off. That should get you going again. The problem is, where did the missing hyd fluid go? It will eventually leak out again sooner or later. If it's a slow leak and you don't mind a little oil dripping on the concrete/ground you are good to go.
I think one of those other "plugs", is an adjustment for max pressure so that you don't get it at full extension, keep pumping anyway, and blow the seals out.
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On Tuesday, March 8, 2016 at 9:13:59 PM UTC-5, >>>Ashton Crusher wrote:

I'll give the rubber plug a try. Thanks.
As far as a leak, I don't see any fluid on the garage floor where it is stored nor do I see any leakage while in use. However, there was oil in the area that I took the picture of, all the way from the flat area to the front of the cylinder. I clean it up for the photo. It was pretty old oil with some dirt mixed, but this was the first time I took the cover plate off to see what was going on, so I don't know how long the oil was there or where it came from.
I bought the jack many years ago on Craigslist and it was old then. I definitely got my $60 out of it, so if filling it doesn't work, I'll consider another used one or maybe go new this time. In the meantime, I'll try to keep an eye on the area I cleaned up to see if any more oil shows up.
Thanks again.
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wrote:

I agree. I have always filled them at the rubber plug.
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