Hi Chris, I am just finishing off restoration of a Mullard MAS 281/15 that has an identical chassis to the Philips 170A. These are fine sets - very sensitive and sound good. If you don't have it already then I recommend you get a copy of the Trader Sheet #770. You can get one here
https://www.service-data.com/product...12/5017/t14812 . You can also get the Philips manufacturer's data sheet but component numbering will be different so my references will be to the Trader. I have attached the mains lead earth wire to a tag on one of the mains transformer chassis mounting bolts which is fine because there is good continuity to chassis. If yours is connected to one of the other transformer bolts then at least check it for continuity using a multimeter on the ohms range from the mains plug earth prong to the receiver's chassis. There should be about one Ohm or less resistance. The transformer is at least partly coated in black pitch so there's at least a possibility that you will otherwise get a bad joint. The screw type electrolytics on these sets rarely survive so you're wise to replace them. There is plenty of room underneath the chassis to solder in smaller modern replacements but do disconnect the old ones first. I also replaced the following capacitors that were all leaky: C36 (0.001uF), C34 (0.047uF), C37 (0.001uF), C30 (0.047uF), C29 (25uF electrolytic - at least 25v wkg voltage needed), C24 (0.047uF), C13 (0.047uF), C13 (0.047uF), C11 (0.047uF), C4 (0.047uF). You don't need to replace the cathode decoupling capacitors C27, C18 or C5 because this will have no beneficial effect. You can use whatever types of capacitor you want as long as they are new and rated at least 400v; 630v is better. I prefer to use the yellow polys. Definitely replace the crumbled wiring - it can be lethal and if short circuits develop that can cause fire or trash the transformers. I can't really see the point of resleeving. I replaced all of the mains transformer wires one at a time using new neoprene insulated wire. As others have said this looks better than PVC which has too bright colours for the period look. The wires are soldered directly to the transformer but I didn't have any trouble replacing them. I've posted 3 pics below. Good luck, cheers, Jerry