Grimston Electrical Tools - Bench Grinder Refurb

Hello

I'm new to this forum so please excuse me if I miss any info out.

I've been refurbishing a vintage bench grinder that I got years ago when a friends Grandad passed away.
It was running surprisngly well but the wirring all looked a bit dangerous and I didnt want to use it regularly without having a proper look at it.

Below are some photos of the inital strip down.

If anyone can help with the electrical side of things, I'd appreciate it.
There is a box which I assume contains a relay, the wires coming from this are in a bad state.
The plstic jackets are all cracked and flaking off in some places, where the wires enter the box, they are bare and frayed.

Can someone advise me on what I need to replace this box?
I could cut it open and see whats inside but, I may just solder new cables onto the old box if there is a risk that I cant find a replacement.

Details of machine:
Grimston Electrical Tools. Circa 1937.
Speed 8900
Phase AC
Cycles 50
230V
Box reads: Max working 400 V. AC Type F. J

Also, if anyone can suggest a good way for me to renew the cables that join the coils, that wuld be really helpful.

Looks like the original color was black or dark grey.
Anyone with experience or knowlage of this brand of machinery?
I will have to chopose some new paint for it once it's all cleaned up.

Some photos:




Any help appreciated.
Thanks for reading.

I've used Grimston "Electriska"pedestal drilling machines quite a bit in previous lives! Nice machines.

You can replace one wire at a time if your unsure of yourself. That is if it is operational. You say it ran good. Take pictures of wiring before disassembling. Find an experienced friend or neighbor if unsure. Blow dust out of the relay. Use heat shrink cable cover.
That looks like a nice grinder.

I have the exact same machine sat at the back of a bench at work. I had just assumed the mystery box was a capacitor, but may be wrong. I would just solder and heat shrink some new wires on and try it.
I need to make up some new arbors for mine, as the wheel size seems unobtainable today, and put the thing back together. It's a good, robust and smooth running grinder. It also matches the Grimston Eleckrista drill sat a few feet from it.
I'll have a look tomorrow and see if I can shed any light on it.
Billy