Gearbox getting a bit tight

[eltax91]

Hi folks. I have an X plate Octavia with the 110 TDi lump in it. I bought it on 75k with full-on history. It's now done 121k and still starts on the button. I use it to do a lot of miles for work (35-40k a year) and over about the last 3k or so, basically last week, the gearbox has started to feel a bit tight when selecting gears.

Mrs Eltax drove it for the first time in ages yesterday and complained of leg and arm ache after driving it! I've obviously not noticed it feeling tighter over time. There is no abnormal crunching or weird noises, like i say, it just feels a bit stiffer. It's not like Mrs E drives a totally different car, she as an A3 with a 100 TDi in it so it should feel similar.

So, what do we reckon folks? I have some gear oil in the shed that i bought for my last car and then sold. Autodata shows it's the correct grade. Would changing the gear oil help, or is my clutch or gearbox on the way out?

I do a lot of my own spannering, but it's not obvious to me where the drain/ re-fill plugs are on the 'box. Should i just keep driving it until the problem gets worse and diagnosius is easier?

[TDI140]

Might be worth investigating further, i had to replace the gearbox in 01 passat 5 speed type 112k on the clock. It started tight on the change and slight noise. The bhin diff exploded on the worst little road in northern ireland last monday mornin, use the car for a runabout but its had £800 spent on it.