G'day last chance.
The Massey 35 when new did not have a hydraulic filter ,It was possible to buy a filter KIT and with a slight modificaltion to the control valve housing the kit could be retrofitted.
You are on the right track ,looking at the videos,the main problem is in the toplink ,draft spring assembly.
To remove ,first remove the alen headed Capscrews ,one each side of the yoke,these are the screws that the toplink Pivots on,remove them,then on then left hand side of the lift cover there is a small alen grub screw that locks the draft nut and stops it coming loose ,take the grub screw out and undo the large NUT with the groves in it ,the nut is about 2.1/2 inches diameter and you will find that the only way to get it out is to heat and drive it round with a dull chisel and patience.
When you have removed the assembly you will find that everything in there is seized and most likely need to be replaced.
To assemble and adjust the draft link assembly, install the draft rod with the cup ,spring into the yoke the end of the draft rod has a cross which allows you to tighten the spring with a screwdriver,tighten ONLY TILL THE SPRING IS HARD TO TURN BY HAND no more the line up the slots with the hole in the yoke, fit the locking pin ,thoroughly clean the threads on the lift cover ,lubricate and install the draft toplink assembly ,TIGHTEN THE BIG NUT UNTIL THE ASSEMBLY IS TIGHT , KEEP TIGHTENING TILL THE SPRING BECOMES LOOSE AND RATTLES IN THERE ,THEN LOOSEN UNTIL EVERYTHING IS TIGHT AGAIN with this done refit and tighten the small grub screw, fit the forks and give it a try , the forks should lift 1000kg or just lift the front wheels of the ground if not try adjusting the big nut just a little bit no more than one quarter turn see if that makes any difference .
Try that and let me know how you went and if you need more information let me know.
Regards.
Hutch.