To the original poster, LawrenceN,
If you have some basic knowledge of how the older/vintage Crosman CO2 air pistols and rifles operate, and basic hands on mechanical skills, the 38T/38C pistols are relatively easy to repair.
As mentioned above, order yourself a complete seal kit (online) from Fox Goods, located in Perth and you will receive the seal kit probably late next week. I think the person processing orders received via email, and the shipping of parts, is a "one man show". Don't even bother to call him, I got the impression his day is fully occupied processing orders and he has next to know time to listen to voice messages, and chatting on the phone. Ordering online works well.
Here is a link to the seal kit you require:
http://scopesandammo.com/storefront/product_info.php/crosman-38-seal-kit-p-583
Earlier this year I purchased two 38T seal kits, and in two evening your 38T will be functioning like new. I rebuilt one pistol at time, so after four evenings I was done.
I have repaired most of my vintage Crosman pistols and rifle in the past. The majority of the older Crosman airguns carried a lot of the same design and function. They were well designed and well constructed. After a number of years the O-rings dry out and get hard, which causes leaks.
After you order the seal kits, go to the Crosman Canada website, they have operator manuals, however, they also have a basic service manual, which provide part numbers plus detailed component and assembly procedures within the drawings. They retain this information for all the models they produced going back in the 1930's or so.
I would suggest downloading the 38T service manual, which you can download for free.
Here is a link to a support section on Crosman's US website, it list information for the older Crosman pistols going back to the 100 pistol and on. Scroll down and download the 38T service manual.
https://support.crosman.com/hc/en-us/categories/200223634-Owner-s-Manuals-and-Parts-Diagrams
Using the service manual information striping the pistol requires basic tools, several sizes of slotted screwdrivers, a 1/4" and 7/16" wrenches.
Since all of the O-rings and seals will be replaced, before you strip the pistol, spray all of the screws fasteners, the two small nuts at the end of the copper tube fittings, one at the piercing assembly, the other end enters the rear of the valve assembly. I use WD40 since it cleans dried grease and gunk, and it will assist you when you take the pistol apart.
Once the parts are ready install the seals, I use a quick shot of brake cleaner to ensure there is no petroleum oils on the areas where the O-rings are seated.
As I am about to fit each seal, I use a smear of silicone lubricant liquid on the O-rings & seals, plus the area where the seals will seat.
If you elect to follow the above suggestion, and are about to begin resealing your 38T, you are welcome to send me a PM, since I am in Mount Hope (Hamilton) and you appear to be in the GTA, I can chat with you over the phone the give you some tips.
Cheers, and a Merry Christmas.