Hi Lou and Welcome to the Forum

As you say, we all have to start somewhere. The fact that you say ­­£4 probably puts you in the UK. This is a totally repairable problem, so I'll start by trying to talk you through the repair, pictures can be added in a later post if needed.

The plastic wire you speak of is called the draw cord as it draws the carriage along as you type. The metal spool is the mainspring drum and is the motor for the carriage. The drum contains a coiled spring just like in an old fashion alarm clock. The draw cord itself is nothing more than a length of monofilament fishing line. Monofilament line was used because it was cheap, but can be a real bearcat to work with as it is so springy, I prefer to use Atwood Micro-Cord if available. 50 to 80 pound (40 to 40 kg) test braided fishing line or kite line also works and is a lot easier to handle.

If you look at the mainspring drum, you will see a keyhole shaped slot on the circumference, this is the anchor point for the draw cord. Now look at the far right back corner of the carriage and you'll see a metal tab with a slot attached to the carriage rail, this is the draw point where the other end of the draw cord attaches.

Once you have some suitable draw cord material, cut a 38cm length and heat seal both ends to stop it from fraying. Tie a figure 8 knot or a double overhand knot in each end and remove all remnants of old draw cord from your typewriter. Move the carriage all the way to the right, press the M-R or double headed arrow key to let the carriage go beyond the left margin stop.

Thread the new draw cord along the back edge of the carriage and slip one end into the draw point on the carriage. Now rotate the mainspring drum about 5 times so you're pushing the top of the drum towards the right side of the machine until the keyhole shaped slot is on top. This will set the mainspring pretension and pull the spring in from the outer circumference of the drum.

Post the other end of the draw cord into the slot and pull the cord into the narrow part of the slot. Hold the cord tight and gradually let the drum rotate until all slack has been taken out of the draw cord. Your typewriter should now work. The mainspring tension may require a little fine tuning to get the correct amount of pull on the carriage, but this should get you going as long as there's nothing else binding the carriage. Hope this points you in the right direction,

Sky